STEAM-BASED HVAC SYSTEM

Abstract

Various methods and devices are provided for heating, cooling, and humidifying a space using a steam-based HVAC system having a steam source, at least one radiator located in a space to be heated or humidified, and a steam and condensate transfer apparatus extending between the steam source and the radiator. The steam and condensate transfer apparatus can have an inner tube configured for transferring steam disposed within an outer tube configured for transferring condensate and the inner tube can be centered within the outer tube such that the outer tube forms an annulus around the inner tube. The tube-in-tube conduit system or double-tube conduit system can take the form of Lego®-like components that can be fitted together to form the structure needed to deliver steam to light-weight flat-panel radiators located within all areas to be heated and/or humidified. The HVAC system can further include a cold air source for delivering cold air into the tube-in-tube conduit system to provide cold air to registers within spaces to be cooled. In one embodiment, the steam and condensate transfer apparatus can be formed from a thermoplastic, for example, polysulfone.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patent application Ser. No. 11/459,023 filed on Jul. 21, 2006 and entitled “Steam Heating System with Tube-in-tube Steam Conduit,” which is hereby expressly incorporated by reference in its entirety.

FIELD

The present invention generally relates to methods and devices for heating and cooling a space using a steam-based heating, ventilating, and air conditioning (HVAC) system.

BACKGROUND

Steam-based heating systems provide simple and reliable techniques for heating in a wide variety of industrial, commercial, and residential applications. Steam is delivered under low pressure of up to 2 psig at 104 degrees Celsius to radiators that transfer the steam condensation heat to the surrounding air. Steam-based heating system have no moving parts, making for easy maintenance and a long life span. Systems having a gas powered pilot thermocouple can also be electricity independent, which is a tremendous advantage for regions prone to electricity shortages, as well as in cold climates. Steam systems today, however, are considered somewhat obsolete due to problems associated with conventional methods and equipment used for transferring the steam and condensate.

Lighter weight copper tubing cannot be used in steam-based systems because the rapid heating by the steam flow will cause damage to soldered joints. Instead, threaded thick-walled steel pipes are conventionally used, requiring periodic draining to remove rust particles that form over time. Conventional steam heating systems are also notoriously inefficient because temperature in a space is rarely maintained at or near a desired set point. Typical systems employ a thermostat in the most distant space to be heated which controls a boiler. Upon a call for heat from the thermostat, steam is generated in the boiler. As the steam pressure increases, the steam enters the metal piping system forcing air to vent through the thermostatic vent valves located on the radiators. Once the hot steam replaces the air in the radiators the valve is closed. The steam must heat and maintain the metal piping system at 214° F. in order to “make a path” to the radiators. The burner continues to function until the temperature setting of the thermostat is reached, at which point the burner is deactivated.

Drawbacks of such conventional systems reside in the fact that metal pipes require a significant amount of heat to reach operating temperature. The pick up factor for steam heating pipes is in a range 1.3-1.5, meaning there is a 30-50% lost heat “load” which later dissipates through insulation into basements or walls, significantly lowering the efficiency of the system. To reduce the proportion of lost heat, massive cast iron radiators are employed for accumulating the heat in a space to be heated. Further, radiators within a space to be heated continue to emit heat after the set point is reached and after the burner is deactivated. Such residual heat raises the temperature within the space beyond the desired set point. As a result, there is a continuous “hunting” cycle wherein the temperature in the most distant space continuously varies from a temperature below the set point to a temperature above the set point. This “hunting” cycle is worse in spaces closer to the boiler because the boiler is only stopped once the correct temperature is reached in the most distant space. The closer the space is to a boiler, the faster it receives heat and the more overheated it may become before the boiler shuts off. This can be partially remedied by setting the desired temperature below what is comfortable in the most distant room, but this increases the frequency of heating cycles and in turn, heat loss from system preheating.

In light of the above-mentioned drawbacks, hydronic and central air systems have been the preferred choice in modern buildings. These newer systems, however, have their own drawbacks when compared with steam-based systems. Hydronic systems are electrically dependent, have moving parts which require maintenance, involve complicated energy consumption metering and computations for residential buildings, and can be damaged if use is discontinued during winter without draining the water from the piping. On average, nearly 50 gallons of water must be supplied and pumped to deliver the same amount of heat as from each gallon of water heated to vapor and then condensed to liquid in a radiator. Further, it is difficult and inefficient to pump the required volume of water to upper floors in high-rise buildings. Typically, operating pressures for such a system are in the range of 30-100 psi, making hydronic systems more prone to leaks. Central air systems are also electrically dependent and require large fans and bulky ductwork that can be difficult to maintain. Ducts and the conditions within the ducts created by central air systems can also encourage the growth of fungus and bacteria. The air moving within the ductwork can circulate dust and odors that must be filtered. In addition, furnaces for both hydronic and central air systems have a significantly shorter life span than boilers typically used in conventional steam-based systems.

Another major difference between steam-based heating systems and hydronic and forced-air systems is the method of heat transfer. A radiator and/or baseboard is heating using both convection (air heating) and radiation (infrared wave emission). The higher the temperature of the radiator, the more heat is emitted by radiation. A typical steam heating radiator temperature is 104 degrees Celsius, which is higher then 80-85 degrees Celsius for hydronic heating. This temperature difference makes a significant difference. When air is used for convection heating, however, it is a poor heat conductor. Further, warm air tends to agitate and carry dust particles and will rise up and escape from a building. In contrast to convection heating, infrared radiation energy is transferred not through the air, but through electromagnetic waves, meaning, the air between the heating unit and the “recipient” does not warm up. A 52% energy savings was reported for an electric radiant heating panel versus electrical baseboard heating. Radiant heating is natural, from a physiologically standpoint, because the human body absorbs up to 99% of radiant heat through the skin. With radiant heat people are typically comfortable at lower air temperatures—as much as 20° F. cooler—partially resulting in energy savings. The proposed steam-based heating system disclosed herein embraces the advantages of electrical radiant heating but with a significantly lower cost of fuel.

Thus, a modernized and improved steam-based system would be preferable both to conventional steam-based systems as well as newer hydronic and central air systems. Accordingly, there is a need for an improved steam-based HVAC system.

SUMMARY OF THE INVENTION

The present invention generally provides for an HVAC system acting a steam-based heating system. The steam-based heating system can include a steam source, at least one radiator located in a space to be heated, and a steam and condensate transfer apparatus extending between the steam source and the at least one radiator. In one embodiment, the steam and condensate transfer apparatus can have an inner tube configured for transferring steam disposed within an outer tube configured for transferring condensate. The inner tube can be centered within the outer tube such that the outer tube forms an annulus around the inner tube. The inner tube can be configured for delivering steam from the steam source to the at least one radiator and the outer tube can be configured to return condensate from the at least one radiator to the steam source. The steam and condensate transfer apparatus can generally be a system of tube-in-tube nipples, elbows, tees, adapters, and clamps extending between the steam source and the at least one radiator.

In one embodiment, the HVAC system can further include a vent controller apparatus positioned in proximity to a vent valve of the radiator and in communication therewith. The steam source can be configured for frequent stops to allow the vent controller apparatus to redistribute steam flows. The vent controller can include a check-valve configured to regulate air into the radiator and a shut-off valve configured to regulate air out of the radiator. A temperature monitoring device can be configured to monitor a temperature of ambient air within the space to be heated and to control the shut-off valve. In an embodiment, the steam source can include a steam source controller and the temperature monitoring device can be configured to communicate information to the steam source controller as to heating requirements based on the temperature of ambient air within the space to be heated.

The radiator can be a light-weight flat panel radiator and it can be divided into two or more sections, each section having its own vent valve and vent controller independently controllable by the temperature monitoring device. In one embodiment, the steam source can be a boiler. In another embodiment, the steam and condensate transfer apparatus can be formed from a thermoplastic, including but not limited to polysulfone. In further embodiments, the steam and transfer apparatus can be formed using an extrusion process.

In another embodiment, the HVAC system can include a humidifier apparatus configured for increasing the humidity of the space to be heated. The humidifier apparatus can include a water reservoir and a paper screen in communication with the water reservoir. The paper screen can be configured to receive and hold water from the water reservoir and to contact hot air from the radiator to cause evaporation of the water held in the paper screen to increase humidity in the space to be heated. In one embodiment, the water reservoir can be in communication with the radiator via condensate tubing and can be configured to receive condensate through the condensate tubing from the radiator. The condensate tubing can have first and second check valves disposed therein between the radiator and the water reservoir. The first and second check valves can be configured to control a flow of condensate into and out of the water reservoir.

In another embodiment, the HVAC system can include a cold air source connected to the steam and condensate apparatus of the steam-based heating system. The steam and condensate apparatus can be further connected to at least one air register for cooling a space to be cooled. The air register can include a control valve and a temperature monitoring device configured to monitor a temperature of ambient air within the space to be cooled. The temperature monitoring device can further be configured to control a shut-off valve on an air register. The cold air source can be an absorption heat pump configured to receive energy from the steam source. The HVAC system can also include an air blower configured to transfer air into a mixing apparatus to throttle chilled water produced by the absorption heat pump. The mixing apparatus can be configured to cool the air, remove dust, and remove excess moisture. The mixing apparatus can be further configured to direct the cooled air into a separator configured to remove liquid water. The separator can be configured to direct the cooled air into the steam and condensate transfer apparatus for delivery to the air register. The liquid water can be configured to be filtered and returned to the absorption heat pump.

In another embodiment, a steam and condensate transfer apparatus is provided and can include a plurality of conduit sections fitted together to extend between a steam source and a radiator. The steam and condensate transfer apparatus can be configured to transfer steam from the steam source to the radiator and to transfer condensate from the radiator to the steam source. Further, each section in the plurality of conduit sections can be formed from an outer tube disposed around an inner tube. In particular, the outer tube can be configured to transfer condensate from the radiator to the steam source and the inner tube can be configured to transfer steam from the steam source to the radiator. In one embodiment, the steam and condensate transfer apparatus can be formed from a thermoplastic material.

Methods are also provided and can include a method for heating a space. In one embodiment, the method can include heating water into steam and introducing the steam into a tube-in-tube conduit system formed from a thermoplastic material. The method can further include delivering steam to a radiator within a first tube of the tube-in-tube conduit system and returning condensate from the radiator within a second tube of the tube-in-tube conduit system. The first tube can be disposed inside the second tube.

The method can also include monitoring a temperature of air in a space to be heated and delivery of the steam to the radiator can be controlled based on the temperature of the air in the space to be heated and based on a pressure in the tube-in-tube conduit system. The method can further include humidifying air in a space to be heated using condensate from the steam delivered to the radiator. Temperatures in a space to be heated can be routinely checked to redistribute steam flows as needed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates one embodiment of a steam-based HVAC system for heating using tube-in-tube conduit for steam and condensate transfer;

FIG. 2A illustrates an embodiment of the assembly of a nipple portion of the tube-in-tube conduit of FIG. 1, showing an inner tube and an outer tube;

FIG. 2B is a side view and a cross-section of one embodiment of an inner tube nipple in the tube-in-tube conduit of FIG. 1;

FIG. 2C is a side view and a cross-section of one embodiment of an outer tube nipple in the tube-in-tube conduit of FIG. 1;

FIG. 2D is a side view of one embodiment of tube-in-tube elbow in the tube-in-tube conduit of FIG. 1;

FIG. 2E is a side view of one embodiment of a tube-in-tube tee for use in line branching of the tube-in-tube conduit of FIG. 1;

FIG. 2F is a side view of one embodiment of tube-in-tube end tee having flexible tubing attached for connecting steam delivery tube and condensate return tube to a radiator in the HVAC system of FIG. 1;

FIG. 3A illustrates an embodiment of the assembly of a shifted nipple portion of tube-in-tube conduit of FIG. 1, showing an inner tube and an outer tube;

FIG. 3B is a side view and a cross-section of one embodiment of a shifted inner tube nipple in the tube-in-tube conduit of FIG. 1;

FIG. 3C is a side view and a cross-section of one embodiment of a shifted outer tube nipple in the tube-in-tube conduit of FIG. 1;

FIG. 3D is a side view of one embodiment of a shifted tube-in-tube male adapter in the tube-in-tube conduit of FIG. 1;

FIG. 3E is a side view of one embodiment of a shifted tube-in-tube female adapter in the tube-in-tube conduit of FIG. 1;

FIG. 3F is a side view of one embodiment of shifted tube-in-tube elbow in the tube-in-tube conduit with shift of FIG. 1;

FIG. 3G is a side view of one embodiment of a shifted tube-in-tube tee in the tube-in-tube conduit of FIG. 1;

FIG. 4A is a representation of one embodiment of a valve system for controlling steam entrance into a radiator at the beginning of a heating cycle in the steam-based HVAC system of FIG. 1;

FIG. 4B is a further representation of one embodiment of a valve system for controlling steam entrance into a radiator during the “breath-in” portion of a heating cycle in the steam-based HVAC system of FIG. 1;

FIG. 5 is a representation of a sectioned flat-panel radiator system for use in the steam-based HVAC system of FIG. 1

FIG. 6A is a representation of a beginning of a heating cycle for in a method for providing a humidifier that can be used in combination with the steam-based HVAC system of FIG. 1;

FIG. 6B is a representation of condensate releasing into a container in a method for providing a humidifier that can be used in combination with the steam-based HVAC system of FIG. 1;

FIG. 6C is a representation of condensate being prevented from going into a container in a method for providing a humidifier that can be used in combination with the steam-based HVAC system of FIG. 1;

FIG. 6D is a representation of condensate draining from a container and a radiator and returning to a tube-in-tube annulus in a method for providing a humidifier that can be used in combination with the steam-based HVAC system of FIG. 1; and

FIG. 7 illustrates one embodiment of a steam-based HVAC system for cooling using tube-in-tube conduit.

DETAILED DESCRIPTION

Certain embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

The present invention provides methods and devices useful for heating, cooling, and humidifying a building using a steam-based HVAC system having a steam source, at least one radiator located in a space to be heated, and a steam and condensate transfer apparatus extending between the steam source and the radiator. The steam and condensate transfer apparatus can include an inner tube configured for transferring steam disposed within an outer tube configured for transferring condensate. In one embodiment, a steam source produces and introduces steam into a thermoplastic tube-in-tube conduit system to be distributed throughout a building. The tube-in-tube conduit system or double-tube conduit system can take the form of Lego®-like components that can be fitted together to form the structure needed to deliver steam to all rooms and/or areas of a building, as will be described in detail below. The tube-in-tube conduit system provides particular advantages for a steam-based heating and cooling system because air in the annulus provides insulation to the inner tube and the steam and condensate flows are separated during a heating cycle. The tube-in-tube structure allows steam to be transferred and delivered using a center tube within the conduit. The outer tube or annulus surrounding the inner tube can then be used for the condensate return. Alternatively or in addition, a separate line can be used for the condensate return.

The steam system of the present invention can be used in any building and/or dwelling as needed. For example, the system can be used for residential purposes in private homes. In addition, the system can be used in office and commercial buildings of all sizes and is particularly efficient in high-rise buildings, as will be described below. For the purposes of the descriptions herein, the term “building” will be used to represent any home, dwelling, office building, educational facility, convention center, and commercial building, as well as any other type of building that can be heated, cooled, and/or humidified as will be appreciated by one skilled in the art.

In an embodiment, a steam source is provided for producing and introducing steam into the steam-based HVAC systems described herein. The steam source can be any source known in the art capable of heating water to produce steam, including a boiler system located within the building to be heated or cooled, and/or an external district heating system capable of supplying steam from a location remote to the building. In one embodiment, a single high-powered boiler can be used. Alternatively, one high-powered boiler can be replaced with a set of smaller capacity boilers that can be fired up individually or in a group, depending on heating requirements. A steam source controller can route the flows of steam throughout the building as needed as the controller receives temperature information from individual radiators, as will be described below. Further, a building's hot water supply can be routed so as to supply the steam source with preheated hot water to decrease the response time of the steam source. A person skilled in the art will appreciate that any steam source capable of producing and introducing steam into the systems described herein can be used as needed. As will also be appreciated, the amount of steam produced and introduced by the steam source will vary depending on the type, size, and requirements of the building.

FIG. 1 illustrates one embodiment of a steam-based HVAC system 10 in which a boiler 12 acts as the steam source. A steam supply line 16 leaves the boiler 12 and transfers steam into an inner tube 13 of a thermoplastic tube-in-tube conduit system beginning at a steam supply main at 14. The steam is transferred through the tube-in-tube conduit system to radiators 20 located within areas or rooms of a building. A valve system 22 located at each radiator 20, as will be described in detail below, can serve to control whether or not the radiator 20 receives steam for heating. A condensate return 24 can transfer the condensate from the radiator to an annulus or outer tube 26 of the tube-in-tube conduit system to be returned to the boiler 12. Alternatively or in addition, the condensate return 24 can directly transfer the condensate to the boiler 12 through the wet return 30. A check-valve, explained below in reference to FIG. 5, positioned within the condensate returns can prevent the outgoing steam from entering the annulus. In the case in which the condensate is returned to the steam source through a separate return line, well-insulated conduit can be used. A person skilled in the art will appreciate that any combination of steam delivery tubing and return tubing can be used depending on the structure and requirements of the building. An inset in FIG. 1 illustrates one exemplary embodiment of a connection means between the metal steam main 14 and the plastic outer tube of tube-in-conduit. As shown, a clamp or bracket system can provide the connection allowing for ease of assembly. To reduce the tubes' thermal expansion difference, the inner plastic tube can extend significantly into the metal tube to lock air in annulus near joint. This technique will preserve connections between dissimilar materials against sharp heating by the steam.

As shown in FIG. 1, the conduit portions are fitted together so that they are continuously connected throughout the transition from section to section. The conduit can be formed from any thermoplastic polymers or plastics known in the art, and the inner and outer tubes can be formed from different materials and/or different grades of materials depending on need and cost requirements. Any thermoplastic material having the required heat characteristics can be used.

In one embodiment, polysulfones can be used to form the tube-in-tube conduit. Polysulfones are particularly advantageous for use in the presently described system because they are high-strength polymers able to maintain their properties up to 150 degrees Celsius, thereby exceeding steam heating working temperatures of a maximum of about 104 degrees Celsius. Further, polysulfones have high compaction resistance and can therefore be used under high pressures, far exceeding pressures associated with steam delivery. Polysulfones can be molded, extruded, welded, and glued, making them easy to form into tubing for conduit and easy to fit and secure together in assembling the required conduit system. In addition, polysulfones can be transparent, allowing for easy assessment of any problems in the system, as well as whether the system needs maintenance or cleaning.

A tube-in-tube structure formed from thermoplastics, such as the polysulfones described above, provides many advantages lacking in conventional steam heating systems that use iron, steel, cast-iron or other metal piping with welded and/or soldered connections. The outer tube/annulus provides a mechanical protective shield, insulation media, and pressure enclosure. Heat loss on the supply steam line is reduced dramatically using thermoplastics because less heat is required to heat and maintain the inner tube at 104 degrees Celsius. In addition, air locked in the outer tube or annulus provides insulation to the steam line inner tube. Because of the reduced heat loss, there is less condensate that forms in the inner tube during the warm-up stage. In addition, the absolute roughness of thermoplastic tubing is orders of magnitude less than metal piping so that the linear velocity of the steam can be higher. This allows for reduced diameter conduit providing the same pressure drop as larger diameter metal piping. Further, the inner tube carrying the steam does not border any pressure difference meaning the inner tube wall need only be thick enough to maintain the tube's shape. In the unlikely event that the inner tube carrying the steam should form a leak, the steam will only be leaked into the enclosed annulus having the same pressure as the inner tube. Should a leak occur in the outer tube, steam will enter annulus and substitute air. A temperature indicator can be provided in the metal piping of the steam main 14 to indicate if a leak ever occurs in the outer tube and to initiate an emergency boiler stop. Finally, using thermoplastics eliminates the need to filter and drain rust particles from the steam and condensate lines.

In particular, in one embodiment shown in FIG. 2A-2F, the conduit parts can be connected by elbows, nipples, and tees, as well as all required adapters, reducers, and expanders. For example, FIG. 2A illustrates a connection of the conduit's outer tube by nipple 50A and nipple 50C illustrates an inner tube connection by way of an inner tube. FIG. 2A illustrates the connection of both tubes simultaneously. The structure of nipples 50A, 50B, and 50C can also be seen in FIGS. 2A-2C. An inner tube nipple 52 having flanges or fins 53 is provided within an exemplary outer tube nipple 54. The flanges 53 are configured to hold the inner tube within the outer tube and can also provide additional mechanical strength to the system. Alternatively or in addition, spacers can be used to center the position of the inner tube within the outer tube. FIG. 2D shows one exemplary embodiment of an elbow portion 56 of tube-in-tube conduit. FIG. 2E illustrates a double tube tee 58 that can be used to branch a steam main line. FIG. 2F illustrates and exemplary tube-in-tube steam conduit end tee 60 that can connect an inner steam line and annulus to a radiator using flexible plastic/rubber tubing 62a, 62b. In one embodiment, teflon-like materials can be used for these flexible connections. In the illustrated embodiment, tube 62a can be used to transfer steam to a radiator, while tube 62b can be used to transfer condensate from the radiator into the tube-in-tube annulus or outer tube. A person skilled in the art will appreciate that any combination of flexible tubing and tube-in-tube conduit can be used to connect the conduit to a radiator.

An exemplary embodiment of shifted tube-in-tube fittings is illustrated in FIGS. 3A-3G. In the illustrated embodiments, the fittings are similar to those shown in FIGS. 2A-2F, but have an inner tube axially shifted within an outer tube by an amount to allow for easier mating techniques. In particular, FIG. 3A illustrates three connections for nipples 70A, 70B, and 70C. As can be seen, an inner tube 71 is axially shifted with respect to an outer tube 72, although both inner and out tubes have the same length. This particular structure allows for easier assembly because the inner tube can be glued or fitted together first, followed by the outer tube. Both approaches shown on FIG. 2 and FIG. 3 are compatible; inner tube should be shorter then outer tube by the shift length to switch from tube-in-tube conduit having a shift to tube-in-tube conduit without the shift. Correspondingly, the inner tube should be longer by a shift length for a switch in the other direction. FIG. 3B shows a shifted inner nipple 74 having fins or flanges 75 for stabilizing the inner tube within an outer tube nipple 76 shown in FIG. 3C. FIGS. 3D-3G illustrates other forms of shifted tube-in-tube conduit including nipples, elbows, and tees.

As will be appreciated by those skilled in the art, any combination of elbows, tees, nipples, and adapters can be used to build the steam-based HVAC systems described herein within a building as needed. One piece extruded tube-in-tube parts can be employed to improve strength and to ease assembling. Inner tubes can be fixed to outer tubes by ribs provisioned in the extrusion process. Fittings similar to the ones illustrated in FIGS. 3A-3G can be used for assembly. In one embodiment, the fittings can be formed by drilling or cutting a solid piece of material, such as a solid piece of polysulfone. To smooth flow turns and reduce pressure drop, connections having lesser angles can be used, as well as the illustrated rectangular ones. Rectangular tubes can be used as well to increase cross section and reduce pressure drop. Additional insulation surrounding the tube-in-tube conduit can be used for conduit sections located in external walls to reduce heat loss.

In the embodiment in which the conduit system is formed from multiple pieces and sections as described above, the conduit sections can be joined or fitted together by any mechanism known in the art. For example, the outer tubes can be clamped and/or glued using snap/grip hose clamps, compression nuts, and/or any other clamping mechanism known in the art while the inner tubes can be glued or tightly fitted together using low inner tube and fittings tolerances in which no glue is necessary.

The thermoplastic tube-in-tube conduit embodiments disclosed therein allows for more frequent boiler stops without significant heat loss. Therefore, a new control method can be employed having routine and mandatory steam source stops for “breath in” cycles. In particular, during a steam-heating cycle, air is pushed out of the radiator by the incoming steam so that the steam can enter the radiator. When the next heating cycle starts, air in the radiator can be locked by a vent controller if the temperature in a heated space exceeds a temperature setting. In an exemplary embodiment, a single thermostat can regulate vent controllers on one or several radiators. Further, the thermostat can control sections of the radiator to be excluded from heating cycle depending on temperature differences from a specified setting. Alternatively or in addition, independent temperature settings can be used for each heated space, and in each space heat consumption can be accommodated independently. A steam source controller can also monitor the signals from under heated spaces to determine the required heat load. Alternatively, the steam source load can be controlled during a heating cycle to keep the system pressure between operating pressure and a maximum system pressure. A person skilled in the art will appreciate that the control method is not limited to that described above, but can vary as needed due to its simplicity and flexibility.

FIGS. 4A and 4B illustrate one exemplary valve system 22 having a vent controller 306 and a commonly used vent valve 304. The vent valve 304 can employ any known principle (bimetal or bellow partially filled with alcohol and water mixture, etc), but generally allows air in and out of the radiator and shuts off when heated by steam. In the illustrated embodiment, the vent controller 306 is a separate unit that includes a shut-off valve 312 and a check valve 314. The vent valve will block the vent controller 306 from the hot steam, thereby protecting it. The vent controller 306 includes two lines associated with the shut-off valve 312 and the check valve 314. As illustrated in FIG. 4A, during routine “breath-in” cycles, a vacuum is created in the radiators by condensed steam and the air is pulled in through one directional check valve 314 and cooled vent valve 304. When the next heating cycle begins and air is pushed out from the radiators, the check valve 314 will automatically shut off. The shut-off valve 312 is normally open and will stay opens if the temperature in the heated space is below a specific setting. If the temperature in the heated space is above the setting, the shut-off valve 312 will close, thereby locking air in the radiator and preventing steam from entering. Depending on the temperature settings, some radiators can be excluded from the next heating cycle, thereby providing a more efficient system. All shut off valves can be independently controlled, as well as manually adjustable if required. During routine “breath in” stops, the insulated inner tubes should lose a minimum amount of heat making overall heat loss reasonably low.

Gas fueled steam-based heating systems can be powered by a pilot light thermocouple and will continue to heat all spaces in an electricity shortage. In this case, if electricity is lost, the controllers may become disabled, thereby preventing valves from locking the radiators based on local temperature settings. In addition, if the shut-off valves 312 are normally closed, they will lock all radiators, but can be manually opened. In one embodiment, a combination of normally closed/open shut off valves can be used to provide heating of selected spaces during an electricity shortage. A person skilled in the art will appreciate that any appropriate combination of vent valves and vent controllers can be used. Alternatively, a single controllable valve synchronized with the steam source controller can be used to perform the job of the vent controller 306.

Any radiators and/or baseboards known in the art can be used to transfer steam heat to a space within a building. A radiator or baseboard that is already in place within a building can be retrofitted to work with the thermoplastic tube-in-tube conduit system by using, for example, flexible plastic connections made from, for example, Teflon, to join older radiator connections with the conduit. In one embodiment shown in FIG. 5, lightweight panel radiators can be used so that shorter stops are required for the “breath-in” cycle because there is less volume to be vented and the radiator cools quicker. A one directional check valve on the condensate return line can be used to lock air in annulus during a heating cycle and to open during “breath in” cycle to flash condensate to the boiler.

The panel radiators can include corrugated plates to provide additional surface area for radiation, as well as a rigid structure. In another embodiment, the radiators can be divided into sections 110A, 110B, and 110C, as shown in FIG. 5, with each section having its own vent controller. Depending on the temperature difference from what is required by the temperature setting, the temperature monitoring device can open more or less sections for steam access, allowing for more precise and flexible temperature control. Sectioned radiators have advantages because constant heat delivery to a particular space at a partial steam “load” is more efficient and comfortable than periodic heating at full steam load. The lightweight panel radiators are particularly convenient because they can be placed anywhere within a space as needed, including under windowsills, on walls, near ceilings, etc. In the embodiment illustrated in FIG. 5, all radiator sections 110A, 110B, and 110C can be serviced by a single steam delivery line 126, as well as a single condensate return line 128. Cross-section A-A illustrates an example of the thinness of the flat panel radiators. In addition, for radiators located on or near the floor, perforated thermoplastic covers can provide a safety shield for hot surfaces. In one embodiment, the covers can be formed from polysulfone which is transparent to infrared waves, lightweight, washable and moldable.

In an embodiment, the system described above can also include humidity control. A radiant heating system, as described above, does not dry the surrounding air as much as a system based on convection heat. Even so, the system described herein can be optionally for humidity control. FIGS. 6A-6D illustrate one embodiment of a method for providing humidity control at each individual radiator 20. In this particular embodiment, an additional line having check valve A is required to connect the condensate return line to a condensate reservoir or container 400. FIG. 6A illustrates the beginning of a heating cycle in which both check valves A and B are closed by pressure in the system. As condensate is formed within the radiator 20 during heating, check valve A ball floats to allow the condensate to flow into a reservoir or container 400, as shown in FIG. 6B. Once condensate is pushed out from radiator, the check valve A closes again, as shown in FIG. 6C. As the heating cycle continues, water from the container 400 is absorbed into a wet paper screen 402 illustrated in FIG. 6A. Water vapor is picked up through evaporation as the hot air passes along the wet paper screen 402, thereby increasing the humidity in the space heated by the radiator 20. As the heating cycle finishes, the system cools, returning to vacuum and causing check valves A and B to open and allow the water to drain from the container 400 and the radiator 20 and to return to the steam source, as shown in FIG. 6D.

The container 400 and the wet paper screen 402 can be contained within a single unit covered by a plastic cover 406 to allow air to pass through the unit and absorb moisture from the wet paper screen 402. Fresh outside air can be directed through the plastic cover 406 to wet paper for humidification. The rate of evaporation can be controlled by changing the size of the section of the wet paper screen 402 that is exposed to the hot air of the radiator 20. The size of the paper screen can be manually or mechanically controlled by “rolling” the screen in or out of a holder. Pure distilled water is circulated through the humidifier to prevent bacteria and fungus growth in the container 400. Water can be periodically added to the system to compensate for the water that is evaporated into the surrounding air. Optionally, a float level shut-off valve can be included within the container to prevent water overflow. A person skilled in the art will appreciate that the above described valve system is exemplary in nature and variations can be easily made to the system. More or fewer check valves can be included depending on system requirements, as well as a different valve system all together if needed.

In one embodiment, the above described steam heating system can also be include an air conditioning system. Cooled air is supplied into the tube-in-tube apparatus and released through registers 524, as shown in FIG. 7. If a combined heating and cooling system is employed, it is preferable to have all controlled valves (radiator vent controllers and those located at the cold air distribution registers) normally closed. In this way, steam will not be released instead of cold air and cold air will not enter radiators. Also, the system pressure can be checked before supplying steam into a new, repaired, and/or modified system. The same temperature controllers used for heating operations can be applied to open normally closed valves if the temperature rises above a specified temperature setting.

While any cool air source or air cooling mechanism known in the art can be used to supply chilled or cold air into the tube-in-tube conduit, in one embodiment, the steam flow normally used for heating is directed to provide power or energy to an absorption heat pump 504, as shown in FIG. 7. As shown, a cooling system 500 is provided having a boiler 502 for providing steam to provide energy to an absorption heat pump 504. Water can be chilled in the absorption heat pump 504 and throttled in a mixer 506 into the fresh make-up/circulation air from a blower 526. Because of the huge contact surface, tiny droplets of cold water can quickly cool air and cause excessive moisture condensation. A separator 528 can then remove excess moisture and dust particles from the cooled air and send the air into the tube-in-tube conduit. Valves 520 can control delivery of the cold air at air registers positioned near the ceiling. Valves positioned near the ceiling air registers 524 can control delivery of cold air. The circulating water from separator 528 can be filtered and cooled again by the absorption heat pump 504.

Cold air from separator with 100% humidity may become too dry when warmed to room temperature. For example, air at 5 degrees Celsius with 100% humidity will drop the humidity to 40% when this air is warmed to a room temperature of 20 degrees Celsius. In this way, the cold air can carry water droplets to increase the humidity of a space to a comfortable level. If the air is in the example is supersaturated, it can carry suspended water particles into the air within a room to raise the humidity from 40% to 70% when the air carrying the water particles is heated to room temperature. In this way, 50% more cooling can be provided from this evaporative cooling. By design, the tube-in-tube conduit is perfectly provisioned for removing condensed moisture droplets from the cold air should it condense within the tube. Smooth tube-in-tube conduit turns, low friction, and high linear velocities within the tubing can facilitate water croplet carry over in a form of mist. Therefore, control of supersaturated water from the separator can improve humidity control and cooling efficiency.

FIG. 7 also illustrates integrated piping system schematic for air registers 524 near the ceiling and three possible mounting positions for the radiator, including a near the ceiling mounted radiator 530A, a wall mounted radiator 530B, and a radiator 530C with a separate condensate return line A person skilled in the art will appreciate that the radiator can be mounted anywhere within a space as needed. This system provides a particular advantage over conventional cooling systems. Instead of moving large volumes of air through bulky ducts, heat exchangers, and filters, only a fraction of clean, cold air or fresh make-up air is needed. Further, because relatively small air volumes are involved and the air is quickly cooled by throttling tiny droplets of water with very high contact surface area, the apparatus can be contained in a compact unit and can achieve high efficiencies when compared with conventional systems.

The embodiments as described above are particularly efficient in high-rise buildings because pumped water is not required to heat upper floors. Further, steam-based heating system maintenance is low because the system does not necessarily require moving parts. The above-described heating and cooling embodiments can also be used as a mobile heating and cooling system. The low weight of the corrosion free tubing in combination with the low pressure requirements is ideal for use in these environments. In an embodiment in which the system is used within a ship, spare drinking water can be used or one small capacity “sacrifice” boiler can be designated to distill sea water for make-up water. This also provides an alternative to the conventional use of thermal liquid circulating pumps, valves, and bypasses. In addition, such systems provide better control flexibility and water logistics when compared to the use of a thermal liquid. In another embodiment for use in closed air cycle systems like submarines, mines, space air conditioning by a cold water mist can be accompanied with carbon dioxide extraction.

A person skilled in the art will appreciate that the above-described embodiments can be implemented in any number of ways and in any number of systems requiring heating, cooling, and humidity control. Accordingly, the application is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

Claims

1. An HVAC system, comprising a steam-based heating system, the steam-based heating system comprising:

a steam source;

at least one radiator located in a space to be heated; and

a steam and condensate transfer apparatus extending between the steam source and the at least one radiator and having an inner tube configured for transferring steam disposed within an outer tube configured for transferring condensate.

2. The HVAC system of claim 1, wherein the inner tube is centered within the outer tube such that the outer tube forms an annulus around the inner tube.

3. The HVAC system of claim 1, wherein the steam and condensate transfer apparatus comprises a system of inner and outer tubes comprising tube-in-tube nipples, elbows, tees, adapters, and clamps extending between the steam source and the at least one radiator.

4. The HVAC system of claim 1, further comprising a vent controller apparatus positioned in proximity to a vent valve of the at least one radiator and in communication therewith.

5. The HVAC system of claim 4, wherein the steam source is configured for frequent routine stops to allow the vent controller apparatus to redistribute steam flows.

6. The HVAC system of claim 4, wherein the vent controller comprises a check-valve configured to regulate air into the at least one radiator and a shut-off valve configured to regulate air out of the at least one radiator and a temperature monitoring device configured to monitor a temperature of ambient air within the space to be heated and to control the shut-off valve.

7. The HVAC system of claim 6, wherein the steam source further comprises a steam source controller and the temperature monitoring device is configured to communicate information to the steam source controller as to heating requirements based on the temperature of ambient air within the space to be heated.

8. The HVAC system of claim 1, wherein the at least one radiator comprises a light-weight flat panel radiator.

9. The HVAC system of claim 1, wherein the at least one radiator is divided into two or more sections, each section having its own vent valve and vent controller independently controllable by the temperature monitoring device.

10. The HVAC system of claim 1, wherein the steam source comprises a boiler.

11. The HVAC system of claim 1, wherein the steam and condensate transfer apparatus is formed from a thermoplastic.

12. The HVAC system of claim 1, wherein the steam and condensate transfer apparatus is formed from polysulfone.

13. The HVAC system of claim 1, wherein at least one component of the steam and condensate transfer apparatus is formed from a solid element using an extrusion process.

14. The HVAC system of claim 1, further comprising a humidifier apparatus configured for increasing the humidity of the space to be heated, wherein the humidifier apparatus comprises a water reservoir and a paper screen in communication with the water reservoir, the paper screen being configured to receive and hold water from the water reservoir, the paper screen being further configured to contact hot air from the at least one radiator to cause evaporation of the water held in the paper screen to increase humidity in the space to be heated.

15. The HVAC system of claim 14, wherein the water reservoir is in communication with the at least one radiator via condensate tubing and is configured to receive condensate through the condensate tubing from the at least one radiator, the condensate tubing having first and second check valves disposed therein between the at least one radiator and the water reservoir, the first and second check valves being configured to control a flow of condensate into and out of the water reservoir.

16. The HVAC system of claim 1, further comprising a cold air source, wherein the cold air source is connected to the steam and condensate apparatus of the steam-based heating system, and wherein the steam and condensate apparatus is further connected to at least one air register in a space for cooling said space.

17. The HVAC system of claim 16, wherein the at least one air register includes a control valve and a temperature monitoring device configured to monitor a temperature of ambient air within the space to be cooled and further configured to control a shut-off valve.

18. The HVAC system of claim 16, wherein the cold air source comprises an absorption heat pump, the absorption heat pump being configured to receive energy from the steam source.

19. The HVAC system of claim 18, further comprising an air blower configured to transfer air into a mixing apparatus to mix with throttled chilled water produced by the absorption heat pump, the mixing apparatus being configured to cool the air, remove dust, and remove excess moisture.

20. The HVAC system of claim 19, wherein the mixing apparatus is further configured to direct the cooled air into a separator configured to remove liquid water, the separator being further configured to direct the cooled air into the steam and condensate transfer apparatus for delivery to the at least one register, wherein the liquid water is configured to be filtered and returned to the absorption heat pump.

21. A steam and condensate transfer apparatus, comprising:

a plurality of conduit sections fitted together to extend between a steam source and a radiator and configured to transfer steam from the steam source to the radiator and to transfer condensate from the radiator to the steam source, wherein each section in the plurality of conduit sections is formed from an outer tube disposed around an inner tube.

22. The steam and condensate transfer apparatus of claim 21, wherein the outer tube is configured to transfer condensate from the radiator to the steam source and the inner tube is configured to transfer steam from the steam source to the radiator.

23. The steam and condensate transfer apparatus of claim 21, wherein the plurality of conduit sections are formed from a thermoplastic material.

24. A method for controlling a temperature of a space, comprising: heating a space by heating water into steam;

introducing the steam into a tube-in-tube conduit system formed from a thermoplastic material; and

delivering steam to a radiator within a first tube of the tube-in-tube conduit system and returning condensate from the radiator within a second tube of the tube-in-tube conduit system, wherein the first tube is disposed inside the second tube.

25. The method of claim 24, further comprising monitoring a temperature of air in a space to be heated.

26. The method of claim 25, wherein delivery of the steam to the radiator is controlled through a radiator vent controller based on the temperature of the air in the space to be heated.

27. The method of claim 24, wherein delivery of the steam to the tube-in-tube conduit system during heating cycles is controlled based on a pressure in the system.

28. The method of claim 24, further comprising humidifying air in a space to be heated using condensate from the steam delivered to the radiator.

29. The method of claim 24, further comprising cooling a space by transferring cold air into the tube-in-tube conduit system to be delivered to one or more cold air registers, the one or more cold air registers delivering the cold air to the space to be cooled.

30. The method of claim 29, further comprising directing the steam to provide energy to a cold air source.