Heat Reclaiming Refrigeration System Using Compound Multi Heat Sink Condenser

A method, and or process, of achieving a double-wall heat recovery refrigeration condenser system, capable, within a single compound condenser, of energy transfer to a heat recovery heat sink, or multiple heat recovery heat sinks, as well as a heat rejection sink, in, any combination of, or all of, the individual heat sinks, in any ratio, requiring no change in the amount of active working fluid, typically a refrigerant, charge requirement. The compound condenser thus eliminates the need for working fluid storage, and controls for controlling said storage, found in typical multi heat sink condenser systems, and also, thus eliminates the complexity associated with said controls and storage. This manner of condenser is used as part of a vapor compression refrigeration system to typically, but not exclusively, reclaim heat from a refrigeration process, for the purpose of heating water.

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Description
FIELD OF THE INVENTION

The present invention relates to refrigeration vapor compression condenser heat exchangers used in refrigeration systems for heat recovery, and more particularly the present invention relates to a compound condenser for transferring condenser heat energy concurrently to multiple heat sinks via separate heat transfer fluids. According to a preferred embodiment, the compound condenser includes a double wall so as to be well suited for either potable or non-potable heat recovery.

BACKGROUND

In the typical vapor compression refrigeration system, various components, such as the compressor, condenser, evaporator and expansion devices, are arranged to transfer heat energy between a fluid in a heat exchange relationship with an evaporator (also known as the heat source) and a fluid in heat exchange relation with the condenser (also known as the heat sink).

It is also known in conjunction with such refrigeration systems to utilize multiple heat exchangers on the discharge, condenser side, of the compressor as desuperheaters and or condensers to transfer the heat from the condensing refrigerant, also known as working fluid, to multiple heat sinks. Often one or more of these heat exchangers are used for the purpose of heat reclaim, such as water heating.

Typical applications include the use of standard air-conditioning units to heat swimming pools and the use of refrigeration or cooling units to heat potable or non potable hot water. Applications are common in industrial, commercial, institutional and residential installations when there is a somewhat coincidental need for both cooling and heat.

However, such known systems have several drawbacks that have inhibited their full commercial acceptance. Principal among such drawbacks are the difficulty of design and the complexity of the heat exchangers and related controls to allow the system to perform effectively over the normal expected operating ranges of the equipment.

The magnitude of the complexity is evidenced by the multiple patents for controls, devices and systems, related to design and control of these systems. Therefore, there is a need for a simplified system that allows the transfer of heat to multiple heat sink fluids in the same vapor compression refrigeration system.

The vapor compression refrigeration system was first described in detail, but never built, by Oliver Evans in 1805. British Patent No. 6662 was granted to Jacob Perkins for the vapor compression refrigeration system in 1835. The working prototype, using ether as a refrigerant, had an evaporator vessel submerged in liquid that provided the heat to vaporize the refrigerant, the gaseous refrigerant was drawn from the evaporator and compressed with a hand operated compressor, the compressed refrigerant was passed through tubing in water where it condensed, the condensed liquid refrigerant was then passed through a pressure reduction valve to start the cycle again. This system contained what has remained the four principle features of a refrigeration system still common today: the evaporator; the compressor; the condenser; and, the expansion device.

A typical vapor compression refrigeration system is shown in FIG. 1 using liquid source to liquid heat sink as per Perkins. However, this schematic could also depict liquid, gas, or solid sources, to liquid, gas, or solid heat sinks, in any combination. Also included is a representation showing liquid to gas proportions and energy movement in the condenser 3. Energy is transferred from an energy (heat) source to the working fluid normally a refrigerant, in an evaporator 1, causing it to evaporate. This gaseous working fluid moves to a compressive device 2 where the pressure is raised, with the associated increase in temperature. This compressed gaseous working fluid then moves to the condenser 3 where the energy is transferred from the working fluid through the condenser to a heat sink fluid causing the gaseous working fluid to condense. The liquid working fluid is returned to the evaporator, through an expansion device 4, to begin the cycle again.

These systems are common, simple, and generally problem free. They are the basis of modern refrigeration vapor compression systems from air-conditioners to artificial ice plants and everything in between. These systems are ubiquitous in our modern life, found in our homes, our businesses, and even our transportation.

A vapor compression refrigeration system is a heat transfer device, i.e. a heat pump. In operation there will always be a reduction of energy, or cooling, on the evaporator or source side of the system and an increase in energy, heat, on the condenser or heat sink side of the system. Although highly efficient in providing heating or cooling as a single product, the use of both simultaneously has always intrigued learned people.

Since early in the invention of the refrigeration, heat pump, cycle, learned people have been struggling to take advantage of the heat rejection part of the process to heat fluids, either directly, or more advantageously, as a free by-product of a needed cooling process. The challenge from the beginning has been that in order to use a simple refrigeration system as taught by Perkins, for simultaneous heating and cooling the need for heating and cooling must occur at the same time, be coincidental, and there must be sufficient cooling and heating loads to allow the system to operate correctly. If either of the loads is insufficient, there is a load differential. If there is a load differential or the loads are not coincidental the total system operation will suffer. The challenge was apparent to the learned as the patent record shows. The evolution to the multi condenser refrigeration system can be clearly seen in the patent record of refrigeration devices used to heat water.

The first teaching on heat reclaim is U.S. Pat. No. 1,331,600 to Wales for a combination cooler water heater. In order to address the differential and coincidental load challenge, Wales limited the amount of water in the hot water tank as well as providing for a brine cooling thermal mass in the cooler. With the use of controlled storage, excess cooling could be stored in the brine thermal mass, and a shortage of condenser energy to properly heat the water could be overcome by reducing the amount of water. Thus both coincidental and differential load problems could be reduced, however they were not necessarily eliminated.

Unfortunately, as can be imagined, even with the benefits provided by the brine and the storage tank, the system would not necessarily provide sufficient heating and or cooling at all times in all applications. The system was capable of levelling the loads; it was not capable of addressing fundamental differences in the loads.

The result is that in the later teachings in U.S. Pat. No. 2,042,812 to Tull, the need for a coincidental load was removed by not specifically using the cooling from the device, in effect wasting the cooling. This system basically heated water with the energy available around the unit. No attempt was made to use the cooling. Some would say a regression in efficient energy usage but an advancement in ensuring that the water heating demand would be met.

In U.S. Pat. No. 2,095,017 to Wilkes the system was once again taught as providing cooling to the room and electric supplemental heat was added to increase water temperature and as a means to ensure hot water production met demand.

In U.S. Pat. No. 2,375,157 again to Wilkes, his previous patent was expanded with teaching on the use of two evaporators connected to two separate heat sources connected to a single hot water generating system. One can imagine that Wilkes recognized that some of the electric heat used in the water tank of his previous patent could be offset if there was more cooling demand.

In U.S. Pat. No. 2,632,306 to Ruff, the teaching provides a solution for the problem of maintaining cooling when no hot water demand exists. This was achieved by bleeding hot water and artificially creating a hot water demand to provide demand cooling.

In U.S. Pat. No. 3,188,829 to Siewert, an additional air-cooled heat exchanger is provided in series with the hot water heat exchanger condenser that acts as the condenser when the demand for hot water has been met. This is a dual heat sink design with the first heat sink being hot water that is heated and the second heat sink is the air that is heated with the excess heat. The second heat sink ensures that the need for cooling is always met when there is no coincidental demand for hot water.

Siewert's teachings ensured that there was no need for coincidental heating of water when cooling was required. This not only ensured that cooling demand was met, but it can reasonably be seen how it could actually increase the total amount of water that could be heated as well, as explained below.

Because the need for balanced coincidental loads had been eliminated, the water heating apparatus could be added to cooling systems which had much greater capacity than the capacity needed just for water heating. With the greater amount of heat available, more water heating could be done when there was coincidental need.

However, Siewert was now moving away from the simple system as taught by Perkins, and the refrigeration system modifications would end up becoming far more complex than simply the addition of another condenser.

One of the key considerations for proper operation of a vapor compression refrigeration system is that the working fluid should be completely liquefied before it enters the expansion device. This ensures that all of the energy that was absorbed by the working fluid in the evaporator through evaporation has been transferred to the condenser through the condensation process, and also that the expansion device works properly. This process of making the gaseous working fluid a liquid occurs in the condenser(s) of a typical vapor compression refrigeration system. To ensure that the working fluid is a liquid the condenser normally cools the working fluid down below its saturation temperature, also known as subcooling. In order for the leaving liquid working fluid to be sub cooled, some portion of the condenser must be filled with liquid working fluid that is being cooled past the condensing temperature.

If there is too little liquid working fluid in the condenser, the proper sub cool design point will not be reached and system operation and performance will be affected negatively. If there is too much liquid working fluid in the condenser, the condensing heat transfer area is reduced also affecting operation and performance in a negative manner. Thus maintaining the designed liquid to gas proportions in the condenser, over the normal operating range of the system, is a very important aspect of optimizing system performance.

With a simple refrigeration system, i.e. a system having one evaporator, and one condenser, the system can typically be designed so that through the expected operating ranges of the equipment, the active operating working fluid charge requirements do not vary beyond the systems ability to accommodate the change.

However, with more complex refrigeration systems designed with multiple condensers, and multiple heat sinks, typically, achieving a fixed unchanging active refrigeration charge is not as easy, resulting in the need for added controls and or working fluid storage.

FIG. 2 shows a system schematic for an air source to a liquid heat sink and then to an air heat sink as per Siewert. However, this schematic could also depict liquid, gas, or solid sources, to liquid, gas, or solid first heat sinks, followed by liquid, gas, or solid second heat sinks, in any combination. This schematic depicts the first heat exchanger operating as a desuperheater (a device that removes energy from the working fluid but does not cool the working fluid enough so that it will condense) and the second operating as the condenser. Also included is a representation showing liquid to gas proportions and energy movement in the condensers.

The various steps of the process are described as follows. Energy is transferred from an energy (heat) source to the working fluid, in an evaporator 1, causing it to evaporate. This gaseous working fluid moves to a compressive device 2 where the pressure is raised, with the associated increase in temperature. The compressed gaseous working fluid then moves to the first series heat exchanger, 3A, which is operating as a desuperheater, where sensible energy can be transferred from the gaseous working fluid to the first heat sink fluid. This energy transfer is not enough to cause the gaseous working fluid to condense. The gaseous working fluid then moves to the next series heat exchanger, 3B, which is operating as a condenser where energy is transferred from the gaseous working fluid through the condenser to a single, second heat sink fluid causing the gaseous working fluid to condense. The liquid working fluid is returned to the evaporator, through an expansion device 4, to begin the cycle again.

FIG. 3 schematically represents the same simplified series multiple condenser vapor compression circuit as shown in FIG. 2, but with the first heat exchanger, 3A, operating as a condenser, and the second heat exchanger, 3B, operating as a subcooler or simply a refrigeration passage. Also depicted are liquid/gas proportions and energy movement representation in the heat exchangers.

The various steps of the process are described as follows. Energy is transferred from an energy (heat) source to the liquid working fluid, in an evaporator 1, causing it to evaporate. This gaseous working fluid moves to a compressive device 2 where the pressure is raised, with the associated increase in temperature. This compressed gaseous working fluid then moves to the first heat exchanger, 3A, which is operating as a condenser where the energy is transferred from the gaseous working fluid through the condenser to a heat sink fluid causing the gaseous working fluid to condense, the working fluid is generally further cooled sensibly in this heat exchanger (subcooled) before it moves to the next heat exchanger, 3B, which can operate as a sub-cooler where further sensible energy can be transferred to the second heat sink fluid or a working fluid passage where no changes are made to the energy content of the working fluid. The liquid working fluid is returned to the evaporator, through an expansion device 4, to begin the cycle again.

In the series condenser system, all of the working fluid goes through all of the heat exchangers in series, allowing all of the working fluid to contact all of the heat sink fluids. As the energy in the gaseous working fluid is released to the condenser the working fluid becomes a liquid. In a series condenser system, three possible operational modes can be envisioned: 1) All of the condensing working fluid energy is transferred in the second heat exchanger; 2) All of the condensing working fluid energy is transferred in the first heat exchanger; 3) Some of the energy is transferred in each of the heat exchangers.

In the first case, if all of the condensing working fluid energy is transferred in the second heat exchanger which is operating as a condenser the first heat exchanger must be full of gaseous working fluid, as no condensing has taken place.

In the second case, if all of the condensing working fluid energy is transferred in the first heat exchanger which is operating as a condenser then all of the working fluid leaving the first heat exchanger must be liquid. This results in the second heat exchanger being completely full of liquid working fluid as the working fluid entering is liquid, and the working fluid leaving must be liquid.

In the third case there will be a condition in between the two extremes of the first case and the second case.

In comparing the first case and the second case, it is clear that the volume of liquid working fluid in each case is very different. In each case the heat exchanger that is acting as the condenser will have roughly the same amount of liquid working fluid. In the first case the other heat exchanger is completely full of gaseous working fluid in the second case it is completely full of liquid working fluid.

In FIG. 2 and FIG. 3, this can be seen clearly by comparing the liquid gas ratio representations. It can be seen that a refrigeration system would need more working fluid to operate in case two (FIG. 3), than in case one (FIG. 2). It can also be envisioned that a refrigeration system with enough working fluid to operate in case two would not operate properly in case one.

To avoid the issues that must be addressed with the changing working fluid charge requirements of these multi heat sink multi condenser systems, it is very common for the first condenser to be operated strictly as a desuperheater, a device that transfers a limited amount of energy, that is insufficient to cause the working fluid to condense, and there are many patents teaching designs and controls on this subject. The disadvantages of this operation is that only a fraction of the energy can be transferred to the first heat sink, and the second heat sink must always be operated.

If the first heat exchanger is designed to be both desuperheater and condenser at different times or in varying ratios, the changes in the required working fluid charge must be addressed by the addition of extra controls and devices.

Siewert recognized the issues associated with the changing active working fluid charge requirements within his design and a great deal of the patent is used to address the components and controls required to properly control these varying active working fluid charges. This is why the refrigeration system shown in FIG. 4, a copy of the drawing in Siewert, modified for comparison, is far more complex than the idealized systems represented in FIGS. 2 and 3.

FIG. 4 shows the same simplified series flow multiple condenser vapor compression circuit schematic with the added controls and devices as taught by Siewert. Items 5-9 have been added to FIG. 2 and FIG. 3. The various steps in the process are described as follows. Energy is transferred from an energy (heat) source to the liquid working fluid, in an evaporator 1, causing it to evaporate. This gaseous working fluid moves to a compressive device 2 where the pressure is raised, with the associated increase in temperature. The compressed gaseous working fluid then moves to the series heat exchangers that can operate in several modes: In the first mode, the first heat exchanger, 3A, operates as a desuperheater, the second heat exchanger, 3B, operates as a condenser and subcooler; In the second mode, the first heat exchanger, 3A, operates as a condenser and the second heat exchanger, 3B, operates as a sub cooler; And finally, in the third mode, the first heat exchanger, 3A, operates as a condenser and the second heat exchanger, 3B, operates as a working fluid passage. Energy is transferred from the gaseous working fluid through the heat exchangers to the heat sink(s), causing the working fluid to condense. The liquid working fluid is returned to the evaporator, through an expansion device 4 to begin the cycle again. Additional components included are: a bypass control valve 5; regulating means 6 for controlling operation of 3B; a working fluid receiver (working fluid storage device) 7; a pressure responsive valve 8 operable to maintain predetermined minimum system pressure at working fluid storage device 7; and, an on-off control valve 9 to regulate operation of the pressure responsive valve 8.

Subsequent patents, which have been many, have maintained the multiple condenser teaching of Siewert. These later teachings have modified the hot water condenser auxiliary condenser arrangement, have introduced parallel condenser designs, have added additional controls for better operation, and taught of different water heating. However, all of the subsequent teachings on this subject have maintained the concept of 2 or more individual heat exchangers capable of being condensers and or desuperheaters, at least one of which heats water.

Although such systems have proven effective at reclaiming and conserving energy, these systems have several fundamental disadvantages that have prevented more widespread acceptance as noted in the following:

1) The multiple operating parameters associated with differing condensing conditions that range from cold water to no water, have a large variable effect on the liquid to gas working fluid proportions in the condensers, resulting in a general requirement for different amounts of active working fluid in the system at different operating conditions. These changes in the required amounts of active working fluid require controls and mechanisms for determining when the amount of active working fluid should change, methods of adding and removing working fluid from the active system, and apparatus to store the extra working fluid.

2) These systems tend to require significantly more working fluid than standard cooling systems, which is an environmental challenge.

3) With the multiple condensers, the controls to operate each, as well as the controls and apparatus described in point 1 above, most such systems are complicated and expensive.

4) In practice, because of the complexity and the variability of operating conditions, service and repair of these systems has been much more difficult.

SUMMARY OF THE INVENTION

The present invention provides a process, and or method of achieving a multi heat sink, heat-recovery compound condenser with a fixed active working fluid charge requirement, capable of eliminating the need for the refrigeration controls and devices that control system working fluid volume typically needed in these systems. This is achieved by having one condenser with additional heat sink fluid heat transfer path(s) within said condenser. These additional heat sink fluid heat transfer paths, when used for heat recovery, are the means of reclaiming the available heat and transferring it to a fluid which can be used to supply heat. The heat-recovery heat sink fluid could be used directly or it could be connected indirectly to the usage device(s) through storage or heat exchange device(s). With such path(s) in place, the condensing working fluid is in contact with both the heat recovery heat sink heat transfer fluid(s) and the heat rejection heat sink heat transfer fluid(s) in such a manner that the condensing working fluid is unaffected by the ratio of the energy going to the individual heat sinks. This method would typically simplify controls, reduce the number of components, reduce the refrigeration charge, and simplify servicing of a refrigeration system, in comparison to other multi heat sink condenser methods with similar functionality.

According to one aspect of the invention there is provided a heat reclaiming refrigeration system for receiving a working fluid therein and for cooling a target fluid, the system comprising:

a compressor device arranged to compress the working fluid from a compressor inlet to a compressor outlet of the compressor device;

a condenser including a working passage arranged to communicate the working fluid therethrough from a condenser inlet to a condenser outlet of the working passage of the condenser, the condenser inlet being in communication with the compressor outlet so as to be arranged to receive the working fluid therefrom;

an expansion device arranged to produce a drop in pressure in the working fluid from the expansion device inlet to the expansion device outlet, the expansion device inlet being in communication with the condenser outlet so as to be arranged to receive the working fluid therefrom; and

an evaporator device including a working passage arranged to communicate the working fluid from an evaporator inlet to an evaporator outlet of the working passage of the evaporator, the evaporator inlet being in communication with the expansion device outlet so as to be arranged to receive the working fluid therefrom and the evaporator outlet being in communication with the compressor inlet such that the compressor inlet is arranged to receive the working fluid from the evaporator outlet;

the working passage of the evaporator device being in heat exchanging relationship with the target fluid so as to be arranged to transfer heat from the target fluid to the working fluid in the working passage of the evaporator device;

the working passage of the condenser comprising a constant passage between the condenser inlet and the condenser outlet which is in concurrent heat exchanging relationship with:

    • i) at least one heat reclaiming passage receiving a respective heat reclaiming fluid therein; and
    • ii) a heat rejection fluid maintained separate from the heat reclaiming fluid of said at least one heat reclaiming passage.

In the preferred embodiment, the working passage includes a double wall boundary between the working passage and said at least one heat reclaiming passage across which heat is transferred from the working fluid to the heat reclaiming fluid. Preferably these boundary walls will be in tight physical contact, possibly with surface enhancements, in order for the heat to be effectively transferred by conduction from one wall to the other. The safety passage between these walls will be vented externally, such as being open to the atmosphere. In the event of a breach of either of the walls the escaping fluid will move through the boundary and out of the system.

Preferably the condenser is operable in a heat rejection mode, a heat reclaiming mode, or a combined heat rejection and heat reclaiming mode.

In the heat rejection mode a controller of the system is arranged to:

    • maintain the heat reclaiming fluid of said at least one heat reclaiming passage in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser; and
    • maintain the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

In the heat reclaiming mode the controller of the system is arranged to:

    • maintain the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and
    • maintain the heat rejection fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser.

In the combined heat rejection and heat reclaiming mode the controller of the system is arranged to:

maintain the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and

maintain the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

According to a second aspect of the present invention there is provided a method of reclaiming heat from a refrigeration system using a working fluid for cooling a target fluid, the method comprising:

i) providing a refrigeration system comprising:

    • a) a compressor device arranged to compress the working fluid from a compressor inlet to a compressor outlet of the compressor device;
    • b) a condenser including a working passage arranged to communicate the working fluid therethrough from a condenser inlet to a condenser outlet of the working passage of the condenser, the condenser inlet being in communication with the compressor outlet so as to be arranged to receive the working fluid therefrom;
    • c) an expansion device arranged to produce a drop in pressure in the working fluid from an expansion device inlet to an expansion device outlet, the expansion device inlet being in communication with the condenser outlet so as to be arranged to receive the working fluid therefrom; and
    • d) an evaporator device including a working passage arranged to communicate the working fluid from an evaporator inlet to an evaporator outlet of the working passage of the evaporator, the evaporator inlet being in communication with the expansion device outlet so as to be arranged to receive the working fluid therefrom and the evaporator outlet being in communication with the compressor inlet such that the compressor inlet is arranged to receive the working fluid from the evaporator outlet, and the working passage of the evaporator device being in heat exchanging relationship with the target fluid so as to be arranged to transfer heat from the target fluid to the working fluid in the working passage of the evaporator device;

ii) providing the working passage of the condenser in the form of a constant passage between the condenser inlet and the condenser outlet which is in concurrent heat exchanging relationship with:

    • a) at least one heat reclaiming passage receiving a respective heat reclaiming fluid therein; and
    • b) a heat rejection fluid maintained separate from the heat reclaiming fluid of said at least one heat reclaiming passage;

iii) arranging the condenser to be operable in a heat reclaiming mode when heating demands on the heat reclaiming fluid are sufficient to maintain efficient operation of the condenser by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser, and by maintaining the heat rejection fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser;

iv) arranging the condenser to be operable in a heat rejection mode when heating demands on the heat reclaiming fluid have been met by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser, and maintaining the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and

v) arranging the condenser to be operable in a combined heat rejection and heat reclaiming mode when heating demands on the heat reclaiming fluid have not been met but are insufficient alone to maintain efficient operation of the condenser by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser, and maintaining the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

The present invention overcomes the disadvantages of the prior art systems in several aspects. In operation, the disclosed design provides a means for the condensing working fluid to be in simultaneous, thermal contact with two or more heat sink heat transfer fluids. In addition, the disclosed system is capable of transferring energy to any one, any combination of, or all of, the individual heat sink heat transfer fluids, in any ratio, within the same condenser structure.

Furthermore, because the condensing process of the working fluid in the disclosed multi heat sink compound condenser is independent of the ratio of energy going to the different heat sinks there is no condenser impact on the needed operational active working fluid charge, resulting from the varying ratios of energy going to each of the heat sink heat transfer fluids. With no variation in operational charge required by the condenser the refrigeration system will operate over the design operation range on a fixed refrigeration charge in the same manner as a single heat sink condenser without the additional: refrigeration controls; refrigeration devices; refrigeration storage; and, extra working fluid associated with prior art multi heat sink refrigeration systems.

In short, the disclosed invention allows a multi heat sink compound condenser to be as simple, from a refrigeration design perspective, as the original vapor compression system patented by Perkins in 1834. Using the disclosed invention, multi heat sink condenser systems, once correctly designed, will operate over their designed operating ranges with fixed active operating working fluid charges, just as a single heat sink condenser system does.

The percentage of energy going to each heat sink can be adjusted by varying the flow of heat transfer fluids to the associated heat sinks in such a manner that is advantageous for the intended purpose.

In some embodiments, a common section of the working passage is in concurrent heat exchanging relationship with both the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage along a full length of the working passage.

Alternatively, the common section of the working passage which is in concurrent heat exchanging relationship with both the heat rejection fluid and the heat reclaiming fluid may extend along only a portion of the length so that one or more auxiliary sections of the working passage in series with the common section is in heating relationship with only one of the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage. For example, one auxiliary section of the working passage immediately adjacent the condenser inlet may be in heat exchanging relationship with only the heat reclaiming fluid corresponding to a desuperheating zone of the condenser.

Preferably the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage are arranged in heat exchanging relationship through different boundary walls of the working passage of the condenser.

The working passage of the condenser may comprise a generally annular passage defined between an outer tubular wall assembly and at least one inner tubular wall assembly extending longitudinally within the outer tubular wall assembly. In this instance, the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage are arranged such that the heat rejection fluid is in heat exchanging relationship with the working fluid through one of the inner and outer tubular wall assemblies and the heat reclaiming fluid is in heat exchanging relationship through another one of the inner and outer tubular wall assemblies which is different than the heat rejection fluid.

When the heat rejection fluid comprises air, preferably the heat rejection fluid is in heat exchanging relationship with the working fluid through an outermost boundary of the working passage of the condenser.

When the working passage of the condenser includes a generally annular portion defined between an outer tubular wall assembly and at least one inner tubular wall assembly extending longitudinally within the outer tubular wall, preferably said at least one inner tubular wall assembly defines a respective first auxiliary passage bound by said at least one inner tubular wall assembly. The condenser may further comprise an auxiliary tubular wall receiving the outer tubular wall assembly substantially concentrically therethrough to define a second auxiliary passage bound between the auxiliary tubular wall and the outer tubular wall assembly.

The heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage are then preferably arranged such that:

    • i) the heat rejection fluid is received in one of the first and second auxiliary passages so as to be arranged in heat exchanging relationship with the working fluid through a corresponding one of the inner and outer tubular wall assemblies; and
    • ii) the heat reclaiming fluid is received in another one of the first and second auxiliary passages different than the heat rejection fluid so as to be arranged in heat exchanging relationship with the working fluid through a corresponding one of the inner and outer tubular wall assemblies different than the heat rejection fluid.

When there is more than one heat reclaiming passage, each receiving heat reclaiming fluid therein, preferably the heat rejection fluid and the heat reclaiming fluid are each arranged in heat exchanging relationship through respective different boundaries of the working passage of the condenser. In this instance, the condenser can include an outer tubular wall assembly and a plurality of independent inner tubular wall assemblies extending alongside one another longitudinally within the outer tubular wall assembly. The working passage of the condenser is thus defined as the volume within the outer tubular wall assembly not occupied by the plurality of inner tubular wall assemblies. The working passage is thus the space extending between the inner and outer tubular wall assemblies and extending longitudinally with the outer tubular wall assembly. The heat rejection fluid is thus in heat exchanging relationship with the working fluid through the outer tubular wall assembly, while one or more heat reclaiming fluids are located in respective ones of the inner tubular wall assemblies so as to be in heat exchanging relationship with the working fluid through the respective inner tubular wall assembly.

There may be provided a heat reclaiming circuit in communication between said at least one heat reclaiming passage of the condenser and a storage device, for example a tank for storing a heat reclaiming fluid therein, or a direct usage device, for example, swimming pools, hot tubs, and washers, or an indirect usage device, for example a heat exchanger, for using the heat reclaim fluid, which has been circulated through said at least one heat reclaiming passage by the heat reclaiming circuit. Each heat reclaiming passage may be associated with: i) a heat reclaiming fluid mover which is arranged to induce a flow of the heat reclaiming fluid through the heat reclaiming passage, ii) a reclaim temperature sensor for determining a temperature of the heat reclaiming fluid prior to entering the condenser, and iii) a controller arranged to increase operation of the heat reclaiming fluid mover in response to a temperature of the heat reclaiming fluid sensed by the reclaim temperature sensor being below a prescribed target temperature. Increasing operation of the heat reclaiming fluid mover can involve turning it on if it is currently not in operation, or simply increasing the operation thereof, for example by increasing speed or increasing the modulation if using a modulating control.

A condensing condition control device may also be provided which is arranged to determine a condensing condition of the working fluid so that the controller may be arranged to decrease operation of the heat reclaiming fluid mover in response to the condensing condition being below a prescribed lower limit. Decreasing operation of the heat reclaiming fluid mover can involve turning it off if it is currently in operation, or simply reducing the operation thereof, for example by reducing speed or reducing the modulation if using a modulating control.

The system may further include: i) a heat rejection fluid mover associated with the heat rejection fluid and arranged to induce a flow of the heat rejection fluid across a boundary of the working passage of the condenser, ii) a condensing condition control device arranged to sense a condensing condition of the working fluid, and iii) a controller arranged to increase operation of the heat rejection fluid mover in response to the condensing condition being above a prescribed upper limit. In some instances the prescribed upper limit is greater than a target condensing condition corresponding to optimal cooling efficiency.

When there is provided a heat rejection fluid mover associated with the heat rejection fluid and arranged to induce a flow of the heat rejection fluid across a boundary of the working passage of the condenser and a condensing condition control device arranged to determine a condensing condition of the working fluid, the controller may also be arranged to increase operation of the heat rejection fluid mover in response to the condensing condition being above a prescribed upper limit if a heating demand on the heat reclaiming fluid of said at least one heat reclaiming passage has been met.

According to another aspect of the present invention there is provided a heat reclaiming method operable within a vapor compression refrigeration circuit typically, but not exclusively, described as containing:

i) an evaporator i.e. a heat exchanger in thermal connection with a heat source fluid on one side and an evaporating working fluid on the other side; the working fluid intake port of the evaporator is connected, either directly or indirectly, with or without devices or control to the discharge port of the expansion device via tubing; the evaporator discharge port is connected, either directly or indirectly, with or without devices or controls, to the suction port of the compressive device via tubing;

ii) a compressive device: capable of raising the pressure, with the associated increase in temperature of a gaseous working fluid; the suction port connected either directly or indirectly, with or without devices or controls, to the discharge port of the evaporator via tubing; the discharge port connected either directly or indirectly, with or without devices or controls, to the intake port of the condenser via tubing;

iii) a condenser i.e. a heat exchanger in thermal contact with a heat sink fluid on one side and condensing working fluid on the other side; the working fluid intake port of the condenser is connected, either directly or indirectly, with or without devices or controls, to the discharge port of the compressive device via tubing; the condenser discharge port is connected, either directly or indirectly, with or without devices or controls, to the intake port of the expansion device via tubing;

iv) an expansion device: a device capable of maintaining a pressure differential between its two ports; the intake port connected either directly or indirectly, with or without devices or controls, to the discharge port of the condenser via tubing; the discharge port connected either directly or indirectly, with or without devices or controls, to the intake port of the evaporator via tubing;

in which the heat reclaiming method comprises configuring a single refrigeration vapor compression condenser with gas or liquid as the primary heat sink heat transfer fluid, to operate as a double wall multi heat sink condenser, with liquid secondary and subsequent heat sink heat transfer fluid(s) as exampled in the detailed descriptions.

The heat reclaiming method is capable of simultaneous thermal connection with multiple heat sink heat transfer fluids, capable of transferring energy to any one, any combination of, or all of, the individual heat sink heat transfer fluids, via separate heat transfer fluid path(s) within the same condenser structure as exampled in the detailed descriptions.

The heat reclaiming method is also capable of maintaining a fixed active working fluid charge, in a multi heat sink refrigeration vapor compression system by the use of a multi heat sink compound condenser, eliminating the need for separate refrigeration storage devices and associated controls as exampled in the detailed descriptions.

Various embodiments of the invention will now be described in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a prior art vapor compression refrigeration circuit;

FIG. 2 is a schematic of a prior art simplified series flow multiple condenser vapor compression circuit operating as a desuperheater to the condenser;

FIG. 3 is a schematic of a prior art simplified series flow multiple condenser vapor compression circuit operating as condenser to sub-cooler;

FIG. 4 is a prior art multiple condenser vapor compression circuit schematic;

FIG. 5A is a front view of a prior art air cooled condenser;

FIG. 5B is an end view of the condenser according to FIG. 5A;

FIG. 5C is a partly sectional front view of one channel of the condenser according to FIG. 5A;

FIG. 5D is an end view of the channel of FIG. 5C;

FIG. 6A is a partly sectional front view of an air cooled condenser with a double wall heat reclaim;

FIG. 6B is an end view of the condenser according to FIG. 6A;

FIG. 6C is a partly sectional front view of one channel of the condenser according to FIG. 6A;

FIG. 6D is an end view of the channel of FIG. 6C;

FIG. 7A is a partly sectional front view of an air cooled condenser with a single wall heat reclaim;

FIG. 7B is an end view of the condenser according to FIG. 7A;

FIG. 7C is a partly sectional front view of one channel of the condenser according to FIG. 7A;

FIG. 7D is an end view of the channel of FIG. 7C;

FIG. 8A is a partly sectional front view of an air cooled condenser with multiple heat reclaims;

FIG. 8B is an end view of the condenser according to FIG. 8A;

FIG. 8C is a partly sectional front view of one channel of the condenser according to FIG. 8A;

FIG. 8D is an end view of the channel of FIG. 8C;

FIG. 9A is a partly sectional front view of a prior art tube in tube coaxial liquid-cooled condenser with heat rejection

FIG. 9B is a partly sectional front view of a section of the condenser according to FIG. 9A;

FIG. 9C is an end view of the condenser section of FIG. 9B;

FIG. 10A is a partly sectional front view of a tube in tube in tube coaxial liquid-cooled condenser with central heat rejection at the inner side of the working passage and double wall heat reclaim at the outer side of the working passage;

FIG. 10B is a partly sectional front view of a section of the condenser according to FIG. 10A;

FIG. 10C is an end view of the condenser section of FIG. 10B;

FIG. 11A is a partly sectional front view of a tube in tube in tube coaxial liquid-cooled condenser with central double wall heat reclaim at an inner side of the working passage and heat rejection at the outer side of the working passage;

FIG. 11B is a partly sectional front view of a section of the condenser according to FIG. 11A;

FIG. 11C is an end view of the condenser section of FIG. 11B;

FIG. 12 is a schematic representation of the condenser in the heat rejection mode.

FIG. 13 is a schematic representation of the condenser in the heat reclaiming mode.

FIG. 14 is a schematic representation of the condenser in the combined heat rejection and heat reclaiming mode.

FIG. 15 is a schematic representation of a preferred embodiment of the heat reclaiming refrigeration system.

FIG. 16 is a partly sectional front view of a section of the condenser according to the system of FIG. 15, illustrating a portion of the working passage.

FIG. 17 is an exemplary compressor performance chart, and

FIG. 18 is an exemplary chart of comparative combined system performance of a cooling system with electric water heating.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

The multi heat sink compound condenser invention can be applied to any vapor compression condenser, including but not limited to: tube in shell; tube in tube; and, tube in fin. The pertinent design consideration is that the condensing working fluid, commonly a refrigerant, is in a simultaneous heat exchange relationship with all of the multiple heat sink fluid heat transfer passages.

It is acknowledged that changes to existing condenser designs will be required to apply the invention.

Following are exemplary embodiments of some common condenser designs as well as those same condenser configurations with possible applications of the invention. These examples are to illustrate the process and or method of application and are in no way exhaustive of all of the refrigeration condenser designs in which the invention can be applied, or all of the manners in which it can be applied by a person skilled in the art.

Referring to the accompanying figures there is illustrated a heat reclaiming refrigeration system generally indicated by reference numeral 10 in FIG. 15. The system 10 circulates a working fluid, therein through the various stages of a refrigeration cycle.

As best shown in FIG. 15, the refrigeration system 10 generally includes a compressor device 12 which includes a compressor inlet 14 and a compressor outlet 16 through which the working fluid is received. The compressor device 12 is arranged to compress the working fluid by raising the pressure, and hence also the temperature, of the fluid from the inlet 14 to the outlet 16

The system 10 also includes a compound condenser 18 which includes a working passage extending therethrough from a condenser inlet 20 to a condenser outlet 22. Various embodiments of the compound condenser 18 are shown in the accompanying figures as described below.

In each instance, the condenser inlet 20 is in communication with the compressor outlet 16 so as to be arranged to receive the working fluid therefrom by using various forms of tubing or the like by direct or indirect connection therebetween. The working fluid passes through the working passage of the condenser 18 such that it is in heat exchanging relationship with various heat sink fluids to be described in further detail below to remove heat from the working fluid and condense the working fluid between the condenser inlet 20 and condenser outlet 22.

The system 10 further generally includes an expansion device 24 having a passage therethrough from an expansion device inlet 26 to an expansion device outlet 28 for receiving the working fluid therethrough. The expansion device inlet is in communication with the condenser outlet 22 so as to be arranged to receive the working fluid therefrom by tubing or the like by direct or indirect connection therebetween.

An evaporator device 30 includes a working passage extending therethrough from an evaporator inlet 32 to an evaporator outlet 34. The evaporator inlet is in communication with the outlet of the expansion device so as to receive the working fluid therefrom by tubing or the like in direct or indirect connection therebetween. The evaporator outlet is in communication with the compressor inlet to complete the refrigeration cycle such that the compressor inlet is arranged to receive the working fluid from the evaporator outlet by tubing or the like in direct or indirect communication therebetween. The working fluid in the working passage of the evaporator device is arranged to be in heat exchanging relationship with a target fluid to be cooled by the system by permitting heat to be transferred from the target fluid to the working fluid in the working passage of the evaporator device. In a typical example, in a room which is to be cooled, the target fluid is air, which is blown across the working passage of the evaporator.

Throughout the various embodiments, the working passage of the condenser 18 is a constant volume passage receiving the working fluid constantly therethrough so that the system maintains a fixed active charge of working fluid throughout operation in the various modes which include the heat reclaiming mode, the heat rejection mode, or the combined heat rejection and heat reclaiming mode described in further detail below. The fixed active charge of working fluid is maintained regardless of the ratio of heat transfer to the heat rejection fluid and heat transfer to the heat reclaiming fluid in the combined heat rejection and heat reclaiming mode.

In some embodiments, as represented schematically in FIG. 15, the working passage may comprise a single channel or multiple channels 33 joined by inlet and outlet manifolds 35 which collectively define a passageway from the condenser inlet 20 to the condenser outlet 22 which is unchanging in volume and configuration.

Generally at least a first portion of boundary walls of a working passage of the condenser 18 is in heat exchanging relationship with a heat rejection fluid. In the embodiments of FIGS. 6A, 7A and 8A described below, the heat rejection fluid may be ambient air or any other fluid surrounding the first portion of the boundary walls which surround the working passage of the condenser 18, that is the heat rejection fluid surrounds the outermost boundary of the working passage in communication with heat transfer fins or the like. Alternatively, as shown in the embodiments of FIGS. 10A and 11A described below, the heat rejection fluid may be contained within a respective heat rejection passage which shares a boundary with the working passage for transferring heat therebetween at the common boundary. The common boundary between the working fluid and the heat rejection fluid is preferably a single wall boundary, but may also take the form of a double wall boundary in further embodiments.

In all instances, at least a second portion of the boundary walls of the working passage of the condenser 18 is also arranged in heat exchanging relationship with one or more heat reclaiming fluids, within respective heat reclaiming passage(s) extending through the condenser 18. The heat reclaiming passage(s) also share a common boundary with the working passage in the condenser 18 for exchanging heat between the working fluid and the heat reclaiming fluid through the common boundary therebetween. The common boundary between the working fluid and the heat reclaiming fluid may be a single wall or double wall boundary as described below.

The first and second portions of the boundary walls of the working passage of the condenser 18 through which heat is exchanged with the heat rejection fluid and the one or more heat reclaiming fluid(s) may each extend along a full length of a common section of the working passage between the condenser inlet 20 and condenser outlet 22. In this manner the working fluid through the condenser 18 is in simultaneous and concurrent heat exchanging relationship with both the heat reclaiming fluid or fluids in the one or more heat reclaiming passages and the heat rejection fluid along a full length of the working passage through the condenser. In this instance the one or more heat reclaiming passages extend in heat exchanging relationship along the working passage from a heat reclaim inlet in proximity to the condenser outlet 22 to a heat reclaim outlet in proximity to the condenser inlet 20.

Alternatively, the common section of the working passage which is in concurrent heat exchanging relationship with both the heat rejection fluid and the one or more heat reclaiming fluids may extend along only a portion of the length of the working passage. In this instance one or more auxiliary sections of the working passage in series with the common section is in heating relationship with only one of the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage. For example, one auxiliary section of the working passage immediately adjacent the condenser inlet may be in heat exchanging relationship with only the heat reclaiming fluid corresponding to a desuperheating zone of the condenser.

The heat reclaiming fluid in the heat reclaiming passage of the condenser 18 is typically part of a heat reclaiming circuit 36 which cycles the fluid in a loop between the passage in the condenser 18 and a storage, heat exchange, or use device 38. A heat reclaim fluid mover 40 is provided in series with the circuit 36 in the form of a pump for example for pumping the heat reclaiming fluid when the fluid is water.

The circuit is typically also provided with an outlet reclaim temperature control device 42 in series between the heat reclaim fluid exiting the condenser 18 and entering the storage, heat exchange, or use device 38 for measuring the temperature of the heat reclaiming fluid exiting the condenser 18. Similarly an inlet reclaim temperature control device 44 can be connected in series between the fluid exiting the storage, heat exchange, or use device(s) and the heat reclaim fluid entering the condenser 18 to monitor the temperature of the heat reclaim fluid entering the condenser 18.

In typical operation, the fluid mover 40 is activated to circulate fluid through the heat reclaiming circuit until the heating demands on the heat reclaiming fluid have been met. This can be accomplished simply by providing a controller which actuates the pump if the sensed temperature of the reclaim fluid at temperature control device 44 falls below a target temperature for the storage, heat exchange, or use device 38 which is determined to satisfy heating requirements.

If the heat reclaiming circuit is combined with a plurality of usage devices, each usage device can include its own heat exchanging circuit in heat exchanging relationship with common or separate storage, heat exchange, or use device(s). A respective controller then controls the circulation of fluid through the respective heat exchanging circuits to meet the respective heat demand of the respective device(s).

The operation of the fluid mover 40 within the heat reclaiming circuit affects the heat transfer to the heat reclaiming fluid passing through the condenser 18 by actively introducing new heat reclaiming fluid for heat exchanging with the working fluid. Similarly the system 10 typically includes a fluid mover 46 associated with the heat rejection fluid(s) to control the flow of heat rejection fluid across respective boundaries of the working passage of the condenser 18 to affect the heat transfer rate to the heat rejection fluid.

In the embodiments of FIGS. 6A, 7A, and 8A the heat rejection fluid mover 46 is a fan which induces a flow of ambient air across the outermost boundary of the working passage of the condenser 18 when actuated to increase the transfer of heat from the working fluid to the heat rejection fluid.

The working passage through the condenser 18 is typically in the form of a passage defined between an outer tubular wall assembly 48 which typically defines an outermost boundary of the working passage and one or more inner tubular wall assemblies 50 typically defining an innermost boundary of the working passage.

The inner tubular wall assembly 50 also typically defines a respective first auxiliary passage therethrough for receiving a heat reclaim fluid P3 or heat rejection fluid P1 therethrough depending on the application. In all instances, typically one of a heat reclaim fluid or a heat rejection fluid is communicated through the passage of the inner tubular wall assembly 50 to be in heat exchanging relationship across the innermost boundary of the working passage defined by the inner tubular wall assembly while a different one of the heat reclaim or heat rejection fluids is in heat exchanging relationship with outer tubular wall assembly 48 defining the outermost boundary wall of the working passage through the condenser 18.

The fluid in heat exchanging relationship across the outermost boundary wall of the working passage may be contained within an auxiliary boundary wall 62 as in the embodiments of FIGS. 10A and 11A for example. In this instance the space between the outer tubular wall assembly 48 and the auxiliary boundary wall 62 defines a second auxiliary passage in addition to the first auxiliary passage bound by the inner tubular wall assembly 50.

In some of the embodiments of the condenser 18, for example as shown in FIGS. 6A, 10A and 11A, when the heat reclaiming fluid is hot water, for example potable water or water for various domestic usages or any non-domestic application, such that it is important to prevent contamination of the water by the working fluid, or the working fluid by the water, due to a leak, one of the tubular wall assemblies 48 or 50 which is between the working fluid P2 and the heat reclaiming fluid P3 comprises a double wall assembly.

The double wall assembly is formed of a first tubular wall 60A and a second tubular wall 60B received concentrically and longitudinally within the first tubular wall 60A so as to define an annular gap therebetween. Tubular wall 60B and 60A are largely in tight heat conductive contact, forming a minimal gap between them. The gap between them is externally vented, generally open to the atmosphere, allowing the fluid from a breach of either 60B or 60A to escape and not contaminate the other.

To assist in operation of the overall system 10 of FIG. 15 which incorporates any one of the embodiments of the condenser 18 therein, the controller of the system also communicates with an inlet condenser control device 52 connected in series with the tubing carrying the working fluid from the compressor device to the condenser 18 and an outlet condenser control device 54 in series with the tubing carrying the working fluid from the outlet of the condenser 18 to the inlet of the expansion device.

In the simplest form of operation of the system, the heat reclaim fluid mover 40 that moves the heat reclaim fluid will run at the same time as the compressor 12 that moves the working fluid. There would be a control device somewhere in the system between the compressor and the expansion device, reacting to operating conditions, which would directly, or indirectly through a system control, cause the heat rejection fluid mover to be activated in response to predetermined conditions. Depending on the application, additional controls can be added to deal with too cold and or too hot heat reclaim temperatures, and to improve performance.

The condenser inlet control device 52 is preferably a pressure and temperature sensor for determining the real temperature and the condensing pressure from which the condensing temperature can then be determined. In alternative embodiments, the control device 52 may comprise either a pressure or temperature sensor for directly measuring the temperature or pressure of the working fluid at the condenser inlet 20.

Operational strategies roughly in order of simplicity with simplest first are as follows:

1) A heat reclaim fluid mover 40 that starts at the same time as compressor 12 for heat reclaim, and the heat rejection fluid mover 46 starting for heat rejection based on high condensing pressure which is measured at control device 52.

2) The same system as 1 with an additional sensor device 44 that monitors the heat reclaim fluid temperature and limits on/off of the heat reclaim fluid mover(s) 40 to prevent over heating of the heat reclaim fluid.

3) The same system as 1 or 2 with control device 52 being used additionally, to cause the system control to limit the heat reclaim fluid mover 40 operation, to control against too low condensing conditions.

4) The same system as 1 or 2 or 3 with an additional control device to the heat rejection fluid mover(s) and or heat reclaim fluid mover(s) to adjust operating pressures based on multiple parameters to maximize efficiency.

Referring generally to the various embodiments of the condenser, the operation of the heat reclaiming refrigeration system 10 of the present invention, as depicted on FIG. 15, and more particularly the compound condenser 18, will now be described in reference to FIGS. 12 through 15.

The compressor 12 is started when there is a demand for cooling. Working fluid in the evaporator 30 is evaporated absorbing heat. The absorption of this heat causes the target fluid in contact with the evaporator to be cooled providing the desired cooling. The compressor 12 compresses the gaseous working fluid coming from the evaporator raising the working fluid's pressure and associated temperature. The working fluid exits the compressor 12 and enters the heat-reclaim condenser 18 following the working fluid path P2. Heat can be transferred from the hot working fluid through the inner wall to the heat-reclaim fluid in P3 or through the outer wall to the heat-rejection fluid in P1. The amount of heat that is transferred to each of the paths is governed by the difference in temperature between the hot working fluid in P2 and each of the other fluids, heat-reclaim in P3 and heat-rejection in P1.

In order to maximize heat transfer to the heat-reclaim fluid the system must be operated in a manner that maximizes the difference in temperature between the hot working fluid in P2 and the reclaim fluid in P3 and minimizes the difference between the hot working fluid in P2 and the heat-rejection fluid in P1. In order to do this the heat rejection fluid mover 46 can be kept switched off, allowing the heat-rejection fluid in P1 to warm up close to the working fluid temperature in P2 and heat reclaim fluid mover 40 can be operated to move the heat reclaim fluid through P3 to a storage, heat exchange, or use device(s) 38 and replenishing through P3 with colder heat-reclaim fluid from the device(s). 38

As long as there is a demand for cooling, the system can operate in this manner transferring most of the heat to the heat-reclaim fluid. In fact with an unlimited supply of cool heat-reclaim fluid no heat-rejection would be required.

The process however, is not unlimited and most heat-reclaim applications do not have unlimited amounts of heat reclaim demand. Refrigeration compressors have operating limits and as the heat-reclaim fluid temperature rises the compressor compression ratio must rise as well in order to maintain the difference in temperature between P2 and P3.

As can be seen in FIG. 17, in a typical compressor performance chart, there are absolute barriers to operation, based on the needed cooling temperature, with lower needed cooling temperatures resulting in lower possible condensing temperatures. In addition, as the needed condensing temperature rises, for a given cooling evaporation temperature, both the compressor capacity and efficiency are reduced.

Example 1 and 2 on FIG. 17 demonstrate this. Example 1 is the maximum condensing temperature, 140 F, for this compressor operating with a 30 F evaporating temperature, whereas Example 2 is at a lower condensing temperature, 110 F, for the same evaporating temperature. The effect of the lower condensing temperature is an increase in cooling capacity of nearly 34% and an increase in the cooling EER (Energy Efficiency Ratio) of over 100%.

In order for this compressor to remain within its recommended operating range for a 30 F evaporating temperature, the condensing temperature must be kept below 140 F, and the lower the condensing temperature can be kept the higher the cooling efficiency will be.

As long as the heat-reclaim fluid is at a temperature that maintains the refrigeration system condensing temperature below design, the heat rejection fluid mover 46 remains off.

When the discharge pressure and or temperature at the control device 52 exceeds the design limits, the heat-rejection fluid mover 46 is started, and operated in such a manner that the condensing temperature of the working fluid circuit is kept at the desired design temperature. This may be done by cycling the heat rejection fluid mover 46 off and on, or preferably, controlling the speed of the heat rejection fluid mover 46.

The effect of the heat rejection fluid mover(s) operating is to increase the difference in temperature between P2 and P1, and to increase the associated heat transfer from P2 to P1. The combined heat transfer of P2 to P3 and P2 to P1 is now capable of maintaining the design condensing temperature, when the heat transfer from P2 to P3 only, was not. The result is that cooling operation and efficiency can be maintained, and heat-reclaim can be maximized for the conditions.

As the temperature of the heat-reclaim fluid in P3 continues to rise, the heat transfer from P2 to P3 will continue to decrease, resulting in the need for the heat transfer from P2 to P1 to increase. This will occur automatically as the discharge control device 52 reacts to the higher compressor discharge pressures and or temperatures by causing the system control to increase the speed or operational frequency of the heat rejection fluid mover 46.

The heat-reclaim fluid passing through P3 can be at any flow rate desired as long as the temperature of the heat-reclaim fluid as measured at temperature control device 44 entering the condenser 18 is, preferably, at or below the temperature of the leaving liquid working fluid as measured by the temperature control device 54. Cooling efficiency and ultimately the amount of energy that can be transferred is enhanced by greater flow of the heat reclaim fluid.

It is possible to have operating conditions where the heat-reclaim temperature 44 may be higher than the liquid working fluid temperature 54 in that case the heat-reclaim fluid flow rate must be controlled so as to ensure that the temperature of the heat-reclaim fluid leaving the condenser 18 as measured at temperature sensor 42 is higher than the entering temperature 44. This is done by varying the capacity of the heat-reclaim fluid mover 40 or alternatively by the use of a modulating valve in the water line. If this is not done there is a possibility that at these conditions the heat-reclaim fluid could actually be cooled by the working fluid.

If storage, heat exchange, or use device 38 reaches the desired maximum temperature as measured by temperature control device 44, heat reclaim fluid mover 40 can be shut off to prevent further heat-reclaim heat transfer. Although the system will automatically adapt to the changing condensing conditions, and maintain the working fluid condensing temperature by modulating the heat rejection fluid mover 46, if there is no need for heat-reclaim, optimally, the operating condensing temperature can be lowered to improve cooling efficiency.

For the purpose of this document the term “Total output power” will be defined as the result of a useful energy transfer, specifically, cooling for air conditioning and the heating of a fluid, expressed in Watts.

The efficiency of a refrigeration system operating in cooling is typically measured in EER, which is defined as BTU/Watt-hr. When the same system is used for heating, the efficiency is measured in COP, which is Watts/Watts, or Watt-hr/Watt-hr, or BTU/BTU. As can be seen they are basically the same formula. The only difference is that the EER will be higher by the ratio of a watt-hr to BTU which is 3.412. In both cases the numerator is the work done (energy output) and the denominator is the energy required to do it (energy input).

As discussed previously, cooling efficiency goes down as condensing temperature goes up. However, the ultimate maximum temperature of the heat-reclaim fluid, for a given heat exchanger design, goes up as the condensing temperature goes up. A higher potential refrigeration condensing temperature not only improves the potential usefulness of the heat-reclaim fluid but can also increase the amount of energy that may be transferred. Fortunately because of the beneficial effect of the heat-reclaim, although cooling efficiency may go down with higher condensing temperatures, total system efficiency, the combination of cooling and heat-reclaim divided by the energy used, will actually remain very high, and higher than cooling efficiency alone at lower condensing temperatures.

The following examples are demonstrative of the concept and are in no way prescriptive as to operation:

Operation 1 (Example 2 from FIG. 17 {cooling only})
Cooling watts=BTUH/3.412=15000/3.412=4396 watts
Input Power=1340 watts

Cooling COP=4396/1340=3.28

Heat of rejection=cooling Watts+input power=4396+1340=5736 Watts
Operation 2 (Example 2 from FIG. 17 {cooling and heat-reclaim})
Cooling watts=BTUH/3.412=15000/3.412=4396 watts
Hot water production=heat of rejection=4396+1340=5736 watts
Total output power=cooling+hot water production=4396+5736=10132 watts
Total system COP=Total output power/power input=10132/1340=7.56
Operation 3 (Example 1 from FIG. 17 {cooling and heat-reclaim}) FIG. 18 Line 8
Cooling watts=BTUH/3.412=11200/3.412=3282 watts

Cooling COP=3282/2130=1.54

Heat of rejection=cooling Watts+input power=3282+2130=5412 watts
Hot water production=heat of rejection=5412 watts
Total output power=cooling+hot water production=3282+5412=8694 watts
COP=Total output power/power input=8694/2130=4.08

Although the cooling efficiency COP in Operation 3 at 1.54 is less than ½ the COP cooling efficiency of Operation 1 at 3.28, the overall total system efficiency, because of the value of the heat-reclaim, is the ratio of 4.08/3.28=24% higher, demonstrating the benefit of operating at higher condensing temperatures if it increases the heat-reclaim energy. Operation 1 is a cooling only COP and has no heating component through heat-reclaim or the use of primary energy.

To get a truer system comparison of operating efficiency, both compared systems must produce the same amount of cooling and water heating, therefore consideration of the energy to heat the hot water in an alternative manner is required. Therefore the cooling only system could be described as a standard cooling system with electric water heating equivalent to the heat-reclaim.

Operation 4 (comparative standard system providing the same cooling and hot water production as Operation 3. with the same cooling efficiency as Example 2. FIG. 17, and standard electric hot water production—FIG. 18 Line 16.)
Cooling watts=BTUH/3.412=11200/3.412=3283 watts
Power=1001 watts

Cooling COP=3283/1001=3.28

5413 watts of hot water
Power for hot water=5413
Total Input power=Input Power of the refrigeration system+Power for hot water=1001+5413=6414 Watts
Total output power=cooling+hot water production=3283+5413=8695 watts
Total system COP using electric heat for hot water=Total output power/power input=8695/6414=1.36

When the additional energy required to heat the hot water is added to the input energy of the standard air conditioning system operating at the lower condensing conditions of Example 2, FIG. 17. as shown in Operation 4, the resultant total system COP is only 1.36.

Even though the cooling COP of the standard system at 3.28 Example 2. FIG. 17. is over 100% greater than the cooling COP of the heat reclaim system of 1.54, operating at the higher condensing conditions of Example 1. FIG. 17, this efficiency advantage is not enough to overcome the less energy efficient production of hot water.
The heat reclaim system has a combined, cooling and water heating, efficiency COP of 4.08 FIG. 18 Line 8, and the standard cooling system, providing the same cooling and hot water, has a combined efficiency COP of 1.36 FIG. 18 Line 16.
The result is that the standard non heat reclaim system will use three times as much energy, 4.08/1.36=3, than the heat reclaim system, to provide the same amount of cooling and hot water.

An operational matrix can be developed for each application to establish the best compromise for condensing temperature operation. It may share characteristics with an exemplary comparative combined system performance chart of a cooling system with electric water heating as shown in FIG. 18. Although, as can be clearly seen, even when as little as 50% of the available heat is recovered, to heat the hot water, the combined efficiency of the heat reclaim system will be over twice as high as the standard system, without heat reclaim, and using electric hot water heat.

When there is a demand for cooling and no demand for heat reclaim, the system operates in the heat rejection mode of FIG. 12. In this instance: the refrigeration compressor 12 is operating, heat reclaim fluid mover 40 is off, heat rejection fluid mover 46 is active, and the system operates as a standard refrigeration system with 100% of condenser heat being rejected. In the heat rejection mode a system control is arranged to maintain the heat reclaiming fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser 18 while also maintaining the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser 18.

When there is a demand for cooling and sufficient heat reclaim demand for full heat reclaim condensing, the system operates in the full heat reclaiming mode of FIG. 13. In this instance: refrigeration compressor 12 is operating; heat reclaim fluid mover 40 is active; the heat rejection fluid mover 46 is off, and the system operates as 100% heat-reclaim unit. In the full heat reclaim mode a system control device is arranged to maintain the heat reclaiming fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser 18, while maintaining the heat rejection fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser 18.

Alternatively when there is a demand for cooling and there is not enough heat reclaim demand for full heat reclaim the system is operable for simultaneous heat reclaim and heat rejection at the condenser 18, as depicted in FIG. 14. In this instance: refrigeration compressor 12 is operating; heat reclaim fluid mover 40 is active; the heat rejection fluid mover 46 is also active. In the combined heat rejection and heat reclaiming mode the controller of the system is arranged to maintain the heat reclaiming fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser 18, and maintain the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser 18. Ideally a control device is used to modulate the heat rejection fluid mover 46 to maintain the compressor condensing conditions as measured at condenser inlet control device 52, and condenser outlet control 54, at the desired operating temperatures and pressures while maximizing heat reclaim.

Higher condensing pressures will typically result in less efficient operation of the refrigeration circuit, which is a negative, and higher reclaim water temperatures, which is a positive. Depending on application and energy costs these operating parameters can be changed to optimize the system performance. Typically this is accomplished by modulating the heat reclaim fluid mover 40 and heat rejection fluid mover 46 to maintain a condensing condition measured at control device 52.

Refrigeration systems also typically operate more efficiently with lower condensing temperatures. As the temperature of the reclaim water rises the condensing temperature must rise to maintain the heat transfer which is governed by the difference in temperature between the working fluid and the temperature of the heat reclaim fluid in the condenser.

At some point the required condensing temperature for transferring all of the heat to the heat-reclaim fluid becomes undesirable or impossible for any of a number of reasons including but not limited to: Lower system capacity; Lower system efficiency; or, System design limits. When full heat transfer to the heat-reclaim fluid is no longer desired or possible some of the heat can still be transferred to the heat-reclaim fluid by operating the condensing circuit in such a manner as to maintain condensing temperatures as high as possible, within the system limitations, based on the net benefit of the reclaimed heat or desired operating conditions. At these conditions all of the compressor superheat and some of the condensing energy can still be transferred to the heat-reclaim fluid.

In the heat reclaiming mode of FIG. 13, the controller is preferably arranged to start the heat reclaiming fluid mover 40 in response to the temperature of the heat reclaiming fluid sensed by the control device 44, being below a prescribed target temperature. The system control is further arranged to decrease or limit operation of the heat reclaiming fluid mover 40 in response to the condensing pressure being below a prescribed lower operational limit or in response to the working fluid condensing conditions being too low, as measured by control device 52. The controller will switch from the heat reclaiming mode to the combined mode by actuating the heat rejecting fluid mover 46 in response to the condensing pressure or temperature condition sensed by the condensing condition control device 52 being above a prescribed upper limit. The prescribed upper limit may be greater than a target condensing temperature or pressure corresponding to optimal cooling efficiency in consideration of heat recovery to increase overall efficiency.

In the heat rejection mode of FIG. 12, the system control is preferably arranged to actuate or increase operation of the heat rejection fluid mover 46 in response to a condensing pressure sensed by the sensor device 52 being above a prescribed upper limit, if a heat reclaim demand on the heat reclaiming fluid of said at least one heat reclaiming passage has been met.

Particulars with regard to various embodiments of the compound condenser 18 will now be described in the following pages.

For comparison purposes, FIGS. 5A through 5D show a prior art air-cooled condenser 200 in which heat transfer fins 202 transfer heat to the heat-rejection heat sink gaseous heat transfer fluid, typically air, from the tubing 204 constraining the gaseous compression working fluid. The tubing 204 has an outer tube wall constraining the gaseous working fluid therein. In this instance, a standard air-cooled condenser creates two fluid paths, the first being the gas that travels over the fins external to the tube, P1, and a second within the inner tube which constrains the gaseous working fluid in P2. The path constraining the gaseous working fluid will be in fluid connection with the compressive device and expansion device as described previously. Heat is transferred across the wall of the tube from the condensing gaseous working fluid into the fins and then into the gaseous heat rejection heat transfer fluid. The gaseous working fluid enters the condenser as a superheated gas. While passing through the condenser the working fluid will first cool sensibly to the saturation point then with no change in temperature it will then condense to a liquid giving off the latent heat. When fully condensed additional sensible cooling will occur and the working fluid will then leave the condenser as a subcooled liquid.

FIGS. 6A through 6D illustrate one embodiment of the condenser 18 according to the present invention in which an air-cooled condenser according to FIGS. 5A through 5D has been enhanced so that the working fluid in passage P2 is in concurrent heat exchanging relation with i) the heat reclaiming fluid in passage P3 and ii) the heat rejection fluid in P1 using the heat transfer fins 202. More particularly the condenser 18 in this instance is a heat recovery, dual sink, air/water-cooled compound condenser. The heat transfer fins 202 transfer heat to the heat rejection heat sink gaseous heat transfer fluid, typically air. The outer tubular wall assembly 48 mounts the fins 202 thereon and defines the outer boundary constraining the gaseous working fluid in P2. The outer tubular wall assembly 48 receives the inner tubular wall assembly 50 concentrically therein to extend longitudinally within the outer tubular wall assembly 48. The inner tubular wall assembly 50 constrains the heat-reclaim liquid heat transfer fluid therein.

In this embodiment, the inner tubular wall assembly 50 defines the double wall assembly comprised of the first tubular wall 60A and the second tubular wall 60B, as previously described. The double wall assembly comprised of the first and second tubular walls thus collectively acts as the barrier or boundary between the working fluid in P2 and the heat reclaim liquid in P3. The first tubular wall 60A of the inner tubular wall assembly 50 defines the inner boundary of the working passage in this instance. The annular gap P4 between the first and second tubular walls 60A and 60B again defines a safety passage, which should be externally vented.

The compound multi-tube in fin condenser 18 shown in FIGS. 6A to 6D thus creates three fluid paths, one is the gas in P1 that travels over the fins external to the tube, a second is the heat reclaim fluid passage P3, and a third is the working fluid passage P2. The safety passage P4 prevents the cross-contamination of the heat-recovery heat transfer fluid and the working fluid in the event of a failure of a tube wall.

The working fluid is constrained in P2. P3 constrains a heat-recovery liquid heat sink heat transfer fluid, and in P1 is the gaseous heat-rejection heat sink heat transfer fluid external to the outer tube in contact with the fin.

P2 constraining the working fluid will be in fluid connection with the refrigeration system compressor device and expansion device as described previously.

There are three possible modes of heat transfer operation within the compound condenser 18 according to FIGS. 6A through 6D as follows.

i) Heat from the gaseous working fluid is transferred through the double wall, inner tubular wall assembly 50 at the inner boundary of P2 to the heat-recovery heat transfer fluid in P3. Little or no heat is transferred from the gaseous working fluid in P2 through the heat transfer fin to P1. This is accomplished by stopping the flow of the gaseous heat-rejection heat transfer fluid through P1 while allowing the flow of the heat-recovery heat transfer fluid through P3.

ii) Heat from the gaseous working fluid is transferred from P2 through the outer tubular wall assembly 48 to the attached heat transfer fins then to the gaseous heat-rejection heat sink heat transfer fluid in P1. Little or no heat is transferred from the gaseous working fluid in P2 through the inner tube wall assembly to the heat-recovery heat transfer fluid P3. This is accomplished by stopping the flow of the heat-recovery heat transfer fluid through P3 while allowing the flow of the gaseous heat-rejection heat transfer fluid through P1.

iii) Heat from the gaseous working fluid is transferred from P2 through the inner tubular wall assembly 50 to the P3 heat-recovery heat transfer fluid; as well as from P2 through the outer walls and fins to the P1 gaseous heat-rejection heat transfer fluid simultaneously. This is accomplished by allowing the flow of all of the heat transfer fluids. To control the amount of energy being transferred to each of the individual heat transfer fluids, the flows of the heat transfer fluids can be varied.

Regardless of the heat transfer mode, the gaseous working fluid enters the condenser 18 as a superheated gas. While passing through the condenser 18, the working fluid will first cool sensibly to the saturation point then with no change in temperature it will condense to a liquid giving off the latent heat. When fully condensed, additional sensible cooling will occur and the working fluid will then leave the condenser 18 as a subcooled liquid.

FIGS. 7A to 7D illustrate another embodiment of the condenser 18 in which the condenser in this instance comprises a compound air-cooled condenser using a single wall between the working fluid and heat reclaim. Although the invention is envisioned as a double wall arrangement as in FIGS. 6A to 6D to protect both the vapor refrigeration circuit and the liquid heat-reclaim heat sink circuit from cross contamination in the event of a failure of a tube wall, the invention is equally applicable to a single wall configuration of the inner tubular wall assembly 50 in the event that the protection is not desired or required.

The operation of the invention in single walled configuration is identical to the operation as described in FIGS. 6A to 6D except that the inner tubular wall assembly 50 in this instance comprises a single wall inner tube so that heat is transferred from the gaseous working fluid in P2 through the single wall inner tube to the heat-reclaim heat sink fluid in P3.

FIGS. 8A to 8D illustrate another embodiment of the condenser 18 in which the condenser comprises a compound air-cooled condenser using more than one heat reclaim. For purposes of manufacturing and or application, the invention can be envisioned with multiple heat recovery heat sink paths, shown with, but not limited to two. If so equipped, this application of the invention would operate in the same general manner as FIGS. 6A to 6D and 7A to 7D if the fluids in all of the paths were connected to the same heat-reclaim heat sink.

If the heat reclaim paths are connected to different heat-reclaim heat sinks, then additionally the proportion of heat being transferred to each of the heat-recovery heat sinks can be modulated by adjusting the fluid flow to the appropriate paths.

More particularly, in the embodiment of FIGS. 8A through 8D, there is provided more than one heat reclaiming passage P3 through the condenser, receiving heat reclaiming fluid therein such that the one or more heat reclaiming fluids are arranged in heat exchanging relationship through respective different boundaries of the working passage of the condenser.

The heat reclaiming passages are defined by respective independent inner tubular wall assemblies 50 extending alongside one another such that the overall grouping of inner tubular wall assemblies 50 may be substantially concentrically received with the outer tubular wall assembly 48. The outer tubular wall assembly 48 again defines the outer boundary of the working passage through the condenser which receives the working fluid in P2. In this instance, the working passage of the condenser includes both a peripheral portion which surrounds the grouping of inner tubular wall assemblies in a circumferential or annular direction adjacent the outer boundary as well as a remaining inner portion between the inner tubular wall assemblies 50. The working passage is thus the volume or space between the outer tubular wall assembly 48 and the collective grouping of inner tubular wall assemblies 50 which define respective boundaries about the working fluid passage. The heat rejection fluid is thus in heat exchanging relationship with the working fluid through the outer tubular wall assembly 48, while the one or more heat reclaiming fluids are located in respective ones of the inner tubular wall assemblies 50 so as to be in heat exchanging relationship with the working fluid through the respective inner tubular wall assemblies.

In the illustrated embodiment of FIGS. 8A through 8D, the inner tubular wall assemblies each comprise a single wall tube. However, similarly to the difference between the embodiments of FIGS. 6A through 6D and 7A through 7D, in a variation to the embodiment of FIGS. 8A through 8D, each inner tubular wall assembly 50 may instead comprise a double wall assembly formed of a first tubular wall 60A and a second tubular wall 60B with an annular safety gap P4, there between across which heat can be transferred.

Turning now to FIGS. 9A through 9C a prior art tube in tube coaxial liquid-cooled condenser 300 is shown. In this instance the condenser includes an outer tube wall 302 which concentrically receives an inner tube wall 304 therein so that the annular space constrained between the inner and outer tube walls defines a heat rejection passage for a heat rejection fluid in P1. The inner tube wall constrains the gaseous working fluid in P2 therein.

Alternatively, the fluids in P1 and in P2 can be readily reversed. In either instance, the tube in tube condenser 300 creates two fluid paths, one between the outer tube and the inner tube and a second within the inner tube. Either one of these paths will constrain the gaseous working fluid with the other constraining a heat-rejection liquid heat sink heat transfer fluid.

The path constraining the gaseous working fluid will be in fluid connection with the compressor device and expansion device as described previously.

Heat is transferred across the wall of the inner tube from the condensing gaseous working fluid to the heat sink heat transfer fluid regardless of the path each has. The heat will transfer from the inner tube path to the outer path if the working fluid is constrained in the inner tube, and from the outer path into the inner tube if the heat sink heat transfer fluid is constrained in the inner tube.

The gaseous working fluid enters the condenser as a superheated gas. While passing through the condenser the working fluid will first cool sensibly to the saturation point then with no change in temperature it will condense to a liquid giving off the latent heat. When fully condensed additional sensible cooling will occur and the working fluid will then leave the condenser as a subcooled liquid.

Turning now to FIGS. 10A through 10C and FIGS. 11A through 11C, two further embodiments of the condenser 18 are shown in which the condenser in both instances generally comprises a tube in tube liquid-cooled condenser as in FIG. 9A which has been modified to include an additional heat reclaim passage, thus creating a compound tube in tube in tube condenser. More particularly, in these embodiments of the invention, the working passage P2 of the condenser comprises a generally annular passage defined between the outer tubular wall assembly 48 at the outer side of the working passage and the inner tubular wall assembly 50 at the inner side of the working passage which extends substantially concentrically and longitudinally within the outer tubular wall assembly.

The inner tubular wall assembly 50 defines a respective first auxiliary passage bound by the inner tubular wall assembly 50 which receives a first one of the heat reclaim or rejection fluids such that the first one of the heat reclaim or heat rejection fluids is in heat exchanging relationship with the working fluid across the inner tubular wall assembly 50.

The condenser 18 of FIGS. 10A to 10C and 11A to 11C differs from the prior art configuration of FIGS. 9A through 9C in that it further includes the auxiliary tubular wall 62 surrounding the outer tubular wall assembly 48 of the working passage so that the auxiliary tubular wall 62 receives the outer tubular wall assembly 48 substantially concentrically therein. The auxiliary tubular wall 62 and the outer tubular wall assembly 48 of the working passage P2 define a second auxiliary passage which is annular in shape between the auxiliary tubular wall 62 and the outer tubular wall assembly 48 of the working passage.

The second auxiliary passage receives a second one of the heat reclaim or heat rejection fluids different from the first one of the fluids received in the first auxiliary passage noted above such that the second one of the heat reclaim or heat rejection fluids is in heat exchanging relationship with the working fluid across the outer tubular wall assembly 48.

Regardless of which of the heat reclaim and heat rejection fluids is received in the first auxiliary passage or the second auxiliary passage, in each instance the heat rejection fluid and the heat reclaiming fluid are received in the first and second auxiliary passages so as to be arranged in heat exchanging relationship with the working fluid at opposing inner or outer sides of the working passage. More particularly, the heat rejection fluid and the heat reclaiming fluid are arranged such that: i) the heat rejection fluid is received in one of the first and second auxiliary passages so as to be arranged in heat exchanging relationship with the working fluid through a corresponding one of the inner and outer tubular wall assemblies; and ii) the heat reclaiming fluid is received in another one of the first and second auxiliary passages different than the heat rejection fluid so as to be arranged in heat exchanging relationship with the working fluid through a corresponding one of the inner and outer tubular wall assemblies different than the heat rejection fluid.

The compound tube in tube in tube condenser 18 again creates three fluid paths, one between the outer auxiliary tube 62 and the outer tubular wall assembly 48 at the outer side of the working passage, a second between the outer tubular wall assembly 48 and the inner tubular wall assembly 50 of the working passage to define the working passage P2, and a third within the inner tubular wall assembly 50 of the working passage. The gaseous working fluid is constrained in P2. The other two paths, P1 and P3, constrain separate heat sink heat transfer fluids.

In each of the embodiments of FIGS. 10A to 10C and 11A to 11C one of the outer tubular wall assembly 48 or the inner tubular wall assembly 50 of the working passage which forms a common boundary with the heat reclaim fluid comprises the double wall assembly. As described above, the double wall assembly in each instance includes a first tubular wall 60A and a second tubular wall 60B which are generally concentric with one another and in tight physical and heat conductive contact with each other so as to allow heat exchange, but not so tight as to prevent the fluid from a breach of either of the tubular walls from escaping through the external venting, which define an annular gap P4 therebetween. The gap is typically open to the atmosphere, preventing a breach of either of the tube walls to allow mixing of the respective fluids. Therefore the double wall assembly created by the first and second tubular walls 60A and 60B is located at the boundary between the working passage and the heat reclaim passage such that the gap in the double wall assembly defines the safety passage P4 to prevent the cross contamination of the heat-recovery heat transfer fluid and working fluid in the event of a failure of a tube wall.

As in all embodiments, the working passage P2 constraining the gaseous working fluid will be in fluid connection to the compressor device and expansion device as described previously.

Turning now more particularly to the embodiment of FIGS. 10A through 10C, in this instance the inner tubular wall assembly 50 of the working passage is a single wall boundary, while the outer tubular wall assembly 48 of the working passage comprises the double wall assembly formed of the first and second tubular walls 60A and 60B as described above. The heat reclaim passage P3 is thus located in the outermost passage between the outer tube wall assembly 48 of the working passage and the auxiliary tubular wall 62, while the heat rejection passage P1 is located in the innermost passage constrained by the inner tubular wall assembly 50 of the working passage.

Alternatively as shown in FIGS. 11A through 11C however, with a water-cooled condenser it is possible to interchange the heat reclaim and heat rejection fluids relative to the embodiment of FIGS. 10A through 10C. In this instance, the outer tubular wall assembly 48 comprises a single wall boundary and the inner tubular wall assembly 50 of the working passage is the double wall assembly formed by the first and second tubular walls 60A and 60B. The heat rejection passage P1 is thus located in the outermost passage between the auxiliary outer wall 62 and the outer tubular wall assembly 48 of the working passage, and the heat reclaim passage P3 is located in the innermost passage constrained by the inner tubular wall assembly 50. FIGS. 11A through 11C thus demonstrates a configuration with the heat transfer fluids interchanged relative to FIGS. 10A and 10C.

With the exception of the location of the double wall assembly, the operation of the condenser 18 of FIGS. 10A to 10C and 11A to 11C are identical. In each instance there are three possible modes of heat transfer operation within the compound condenser 18 as described in the following.

i) Heat from the gaseous working fluid is transferred from P2 through the double wall boundary of the working passage to the heat reclaim heat sink fluid in P3. Little or no heat is transferred from the gaseous working fluid in P2 to heat the rejection fluid in P1. This is accomplished by stopping the flow of the heat rejection heat transfer fluid through P1, while allowing the flow of the heat-reclaim heat transfer fluid through P3.

ii) Heat from the gaseous working fluid is transferred through the single wall boundary of the working passage from P2 to the heat-rejection fluid in P1. Little or no heat is transferred from the working fluid in P2 to the heat reclaim heat transfer fluid in P3. This is accomplished by stopping the flow of the heat-reclaim heat transfer fluid through P3, while allowing the flow of the heat-rejection heat transfer fluid through P1.

iii) Heat from the gaseous working fluid is transferred from P2 to both the heat-rejection heat transfer fluid in P1 and the heat-reclaim heat transfer fluid in P3 simultaneously. This is accomplished by allowing the flow of both of the heat sink heat transfer fluids. To control the amount of energy being transferred to each of the individual heat transfer fluids the flows of the heat transfer fluids can be varied.

Regardless of the heat transfer mode, gaseous working fluid enters the condenser as a superheated gas. While passing through the condenser the working fluid will first cool sensibly to the saturation point then with no change in temperature it will condense to a liquid giving off the latent heat. When fully condensed additional sensible cooling will occur and the working fluid will then leave the condenser as a subcooled liquid.

As with the air-cooled condenser application of the teachings, with a water-cooled condenser it is possible to configure the invention with single wall heat exchangers or multiple heat sink tubes without varying the intent of the invention. In addition with a water-cooled condenser it is possible to configure the invention with an additional double wall between the working fluid and the heat-rejection fluid without varying the intent of the invention.

As stated previously, the preceding are exemplary embodiments of some common condenser designs as well as those same condenser configurations with possible applications of the invention.

These examples are to illustrate the process and or method of application and are in no way exhaustive of all of the refrigeration condenser designs in which the invention can be applied or all of the manners in which it can be applied by a person skilled in the art.

When properly designed, the compound multi heat sink condenser, as disclosed, will result in a multi heat sink refrigeration system with a fixed active working fluid charge requirement within the condenser that is largely unaffected by the ratio of the energy being transferred to each of the heat sinks allowing the refrigeration system to operate identically to a single heat sink system.

FIGS. 12, 13, and 14 illustrate compound multi heat sink condenser, vapor compression circuit schematics which are applicable to all of the compound condenser embodiments described herein and should be contrasted with prior art arrangements in FIGS. 2 and 3. More particularly, FIGS. 12, 13 and 14 illustrate simplified, compound multi heat sink condenser, vapor compression circuit schematics, including graphical depictions of liquid to gas ratios, active working fluid charge requirements and energy movement representation in the condensers. In each instance:

1) Energy is transferred from an energy (heat) source to a liquid working fluid, in an evaporator, causing it to evaporate.

2) This gaseous working fluid moves to a compressive device where the pressure is raised, with the associated increase in temperature.

3) This gaseous working fluid then moves to the condenser, where the energy can be transferred from the gaseous working fluid through the condenser to any or all of the multiple heat transfer fluids, either individually or simultaneously in any ratio, based on the respective temperature and flow of the heat transfer fluids, causing the gaseous working fluid to condense. In FIG. 12 energy is moving from the working fluid in P2 to the first heat transfer fluid in P1; which in this case is the air in contact with the fins. In FIG. 13 energy is moving from the working fluid in P2 to the second heat transfer fluid in P3, which in this case is the heat-reclaim water constrained in the inner tube. In FIG. 14, energy is moving from the working fluid in P2 to both heat transfer fluids in P1 and in P3, simultaneously.

4) The liquid working fluid is returned to the evaporator, through an expansion device either directly or with the addition of other controls, heat exchangers or devices, to begin the cycle again.

As can be seen clearly, by comparing the graphical depictions of liquid to gas ratios, active working fluid charge requirements and energy movement representation in the condensers for each drawing, the heat sink, or sinks, that the energy is moving to has no impact on the ratio of liquid to gas nor on the active working fluid charge requirements within the compound condenser.

It is understood that while certain forms of the present invention associated with certain refrigeration processes have been illustrated and described herein, the invention is not to be limited to the specific forms, refrigeration processes, or arrangements of parts described and shown.

In addition variations of the specific construction and arrangement of the heat exchanger disclosed above can be made by those skilled in the art without departing from the invention as defined in the claims.

Some examples of these variations include but are not limited to: i) Multi wall internal piping to meet potable water requirements in some jurisdictions; ii) Heat transfer enhancements to the tubing, either internally or externally; including but not limited to the use of fins; deformation of the tubes and other methods to increase surface area, etc; iii) The addition of controls or monitoring equipment to the refrigeration circuit; and iv) The use of flow control on any, or all, of the condenser heat transfer fluids.

Since various modifications can be made in the invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims

1. A heat reclaiming refrigeration system for receiving a working fluid therein and for cooling a target fluid, the system comprising:

a compressor device arranged to compress the working fluid from a compressor inlet to a compressor outlet of the compressor device;
a condenser including a working passage arranged to communicate the working fluid therethrough from a condenser inlet to a condenser outlet of the working passage of the condenser, the condenser inlet being in communication with the compressor outlet so as to be arranged to receive the working fluid therefrom;
an expansion device arranged to produce a drop in pressure in the working fluid from an expansion device inlet to an expansion device outlet, the expansion device inlet being in communication with the condenser outlet so as to be arranged to receive the working fluid therefrom; and
an evaporator device including a working passage arranged to communicate the working fluid from an evaporator inlet to an evaporator outlet of the working passage of the evaporator, the evaporator inlet being in communication with the expansion device outlet so as to be arranged to receive the working fluid therefrom and the evaporator outlet being in communication with the compressor inlet such that the compressor inlet is arranged to receive the working fluid from the evaporator outlet;
the working passage of the evaporator device being in heat exchanging relationship with the target fluid so as to be arranged to transfer heat from the target fluid to the working fluid in the working passage of the evaporator device;
the working passage of the condenser comprising a constant passage between the condenser inlet and the condenser outlet in which at least a section of the constant passage is in concurrent heat exchanging relationship with: i) at least one heat reclaiming passage receiving a respective heat reclaiming fluid therein; and ii) a heat rejection fluid maintained separate from the heat reclaiming fluid of said at least one heat reclaiming passage.

2. The system according to claim 1 wherein the working passage includes a double wall boundary between the working passage and said at least one heat reclaiming passage across which heat is arranged to be transferred from the working fluid to the heat reclaiming fluid, the double wall boundary comprising a pair of boundary walls defining an externally vented safety passage therebetween.

3. The system according to claim 1 wherein the condenser is operable in a heat rejection mode in which a system control is arranged to:

maintain the heat reclaiming fluid of said at least one heat reclaiming passage in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser; and
maintain the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

4. The system according to claim 1 wherein the condenser is operable in a heat reclaiming mode in which a system control is arranged to:

maintain the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and
maintain the heat rejection fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser.

5. The system according to claim 1 wherein the condenser is operable in a combined heat rejection and heat reclaiming mode in which a controller of the system is arranged to:

maintain the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and maintain the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

6. The system according to claim 1 wherein the working passage is in concurrent heat exchanging relationship with both the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage along a full length of the working passage.

7. The system according to claim 1 wherein a common section of the working passage is in concurrent heat exchanging relationship with both the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage and at least one auxiliary section of the working passage is in heating relationship with only one of the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage.

8. The system according to claim 1 wherein the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage are arranged in heat exchanging relationship through different boundary walls of the working passage of the condenser.

9. The system according to claim 8 wherein the working passage of the condenser comprises a generally annular passage defined between an outer tubular wall assembly and at least one inner tubular wall assembly extending longitudinally within the outer tubular wall assembly, and wherein the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage are arranged such that the heat rejection fluid is in heat exchanging relationship with the working fluid through one of the outer tubular wall assembly and said at least one inner tubular wall assembly and the heat reclaiming fluid is in heat exchanging relationship through another one of the outer tubular wall assembly and said at least one inner tubular wall assembly which is different than the heat rejection fluid.

10. The system according to claim 8 wherein the heat rejection fluid comprises air in heat exchanging relationship with the working fluid through an outermost boundary of the working passage of the condenser.

11. The system according to claim 1 wherein:

the working passage of the condenser includes a generally annular portion defined between an outer tubular wall assembly and at least one inner tubular wall assembly extending longitudinally within the outer tubular wall assembly;
said at least one inner tubular wall assembly defining a respective first auxiliary passage bound by said at least one inner tubular wall assembly;
the condenser further comprises an auxiliary tubular wall receiving the outer tubular wall assembly substantially concentrically therethrough to define a second auxiliary passage bound between the auxiliary tubular wall and the outer tubular wall assembly; and
the heat rejection fluid and the heat reclaiming fluid of said at least one heat reclaiming passage being arranged such that the heat rejection fluid is in heat exchanging relationship with the working fluid through one of the outer tubular wall assembly and said at least one inner tubular wall assembly and the heat reclaiming fluid is in heat exchanging relationship through another one of the outer tubular wall assembly and said at least one inner tubular wall assembly which is different than the heat rejection fluid.

12. The system according to claim 1 wherein said at least one heat reclaiming passage comprises a plurality of heat reclaiming passages, each receiving a respective heat reclaiming fluid therein, and wherein the heat rejection fluid and each heat reclaiming fluid are arranged in heat exchanging relationship through respective different boundaries of the working passage of the condenser.

13. The system according to claim 12 further comprising an outer tubular wall assembly and a plurality of independent inner tubular wall assemblies extending alongside one another longitudinally within the outer tubular wall assembly such that:

the working passage of the condenser is defined between the outer tubular wall assembly and the plurality of independent inner tubular wall assemblies extending longitudinally within the outer tubular wall assembly;
the heat rejection fluid is in heat exchanging relationship with the working fluid through the outer tubular wall assembly; and
each heat reclaiming fluid is located in a respective one of the inner tubular wall assemblies so as to be in heat exchanging relationship with the working fluid through the respective inner tubular wall assembly.

14. The system according to claim 1 further comprising a heat reclaiming circuit in communication between said at least one heat reclaiming passage of the condenser and a storage device for storing heat reclaiming fluid therein which has been circulated through said at least one heat reclaiming passage by the heat reclaiming circuit.

15. The system according to claim 14 in combination with a plurality of usage devices, each usage device including a usage circuit in communication with the storage device and a controller for controlling circulation of the usage circuit between the storage device and the respective usage device according to a respective heat demand of the respective usage device.

16. The system according to claim 1 wherein said at least one heat reclaiming passage includes a heat reclaiming fluid mover associated therewith and arranged to induce a flow of the heat reclaiming fluid through the heat reclaiming passage, a reclaim temperature sensor device for determining a temperature of the heat reclaiming fluid prior to entering the condenser, and a system control arranged to increase operation of the heat reclaiming fluid mover in response to the temperature of the heat reclaiming fluid sensed by the reclaim temperature sensor device being below a prescribed target temperature.

17. The system according to claim 16 further comprising a condensing condition sensor device arranged to determine a condensing condition of the working fluid, a system control being arranged to decrease operation of the heat reclaiming fluid mover in response to the condensing condition being below a prescribed lower limit.

18. The system according to claim 16 further comprising a heat rejection fluid mover associated with the heat rejection fluid and arranged to induce a flow of the heat rejection fluid across a boundary of the working passage of the condenser and a condensing condition sensor device arranged to determine a condensing condition of the working fluid, a system control being arranged to increase operation of the heat rejection fluid mover in response to the condensing condition being above a prescribed upper limit.

19. The system according to claim 18 wherein the prescribed upper limit is greater than a target condensing condition corresponding to optimal cooling efficiency.

20. The system according to claim 1 further comprising a heat rejection fluid mover associated with the heat rejection fluid and arranged to induce a flow of the heat rejection fluid across a boundary of the working passage of the condenser and a condensing condition sensor device arranged to determine a condensing condition of the working fluid, a system control being arranged to increase operation of the heat rejection fluid mover in response to the condensing condition being above a prescribed upper limit if a heating demand on the heat reclaiming fluid of said at least one heat reclaiming passage has been met.

21. A method of reclaiming heat from a refrigeration system using a working fluid for cooling a target fluid, the method comprising:

i) providing a refrigeration system comprising: a) a compressor device arranged to compress the working fluid from a compressor inlet to a compressor outlet of the compressor device; b) a condenser including a working passage arranged to communicate the working fluid therethrough from a condenser inlet to a condenser outlet of the working passage of the condenser, the condenser inlet being in communication with the compressor outlet so as to be arranged to receive the working fluid therefrom; c) an expansion device arranged to produce a drop in pressure in the working fluid from an expansion device inlet to an expansion device outlet, the expansion device inlet being in communication with the condenser outlet so as to be arranged to receive the working fluid therefrom; and d) an evaporator device including a working passage arranged to communicate the working fluid from an evaporator inlet to an evaporator outlet of the working passage of the evaporator, the evaporator inlet being in communication with the expansion device outlet so as to be arranged to receive the working fluid therefrom and the evaporator outlet being in communication with the compressor inlet such that the compressor inlet is arranged to receive the working fluid from the evaporator outlet, and the working passage of the evaporator device being in heat exchanging relationship with the target fluid so as to be arranged to transfer heat from the target fluid to the working fluid in the working passage of the evaporator device;
ii) providing the working passage of the condenser in the form of a constant passage between the condenser inlet and the condenser outlet which is in concurrent heat exchanging relationship with: a) at least one heat reclaiming passage receiving a respective heat reclaiming fluid therein; and b) a heat rejection fluid maintained separate from the heat reclaiming fluid of said at least one heat reclaiming passage;
iii) arranging the condenser to be operable in a heat reclaiming mode when heating demands on the heat reclaiming fluid are sufficient to maintain efficient operation of the condenser by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser, and by maintaining the heat rejection fluid in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser;
iv) arranging the condenser to be operable in a heat rejection mode when heating demands on the heat reclaiming fluid have been met by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in a passive and non-flowing condition in heat exchanging relationship with the working passage of the condenser, and maintaining the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser; and
v) arranging the condenser to be operable in a combined heat rejection and heat reclaiming mode when heating demands on the heat reclaiming fluid have not been met but are insufficient alone to maintain efficient operation of the condenser by maintaining the heat reclaiming fluid of said at least one heat reclaiming passage in an active and flowing condition in heat exchanging relationship with the working passage of the condenser, and maintaining the heat rejection fluid in an active and flowing condition in heat exchanging relationship with the working passage of the condenser.

22. The method according to claim 21 including maintaining a fixed active charge of working fluid throughout operation in either the heat reclaiming mode, the heat rejection mode, or the combined heat rejection and heat reclaiming mode regardless of the ratio of heat transfer to the heat rejection fluid and heat transfer to the heat reclaiming fluid in the combined heat rejection and heat reclaiming mode.

Patent History
Publication number: 20150007594
Type: Application
Filed: Jul 3, 2013
Publication Date: Jan 8, 2015
Inventors: Lance C. Laufer (Winnipeg), David A. Jones (Winnipeg)
Application Number: 13/935,202
Classifications
Current U.S. Class: Transferring Heat Between Diverse Function Portions Of Refrigeration Cycle (62/113); Compressor-condenser-evaporator Circuit (62/498)
International Classification: F25B 29/00 (20060101);