Integrated Thermal System

Abstract

A thermal energy system includes a solar energy collector, a ground loop having an inlet and an outlet, and a heat pump. A first fluid conduit extends from the outlet to the solar energy collector, and from the solar energy collector to the inlet, for transporting a heat exchange fluid, from the outlet to the inlet through the solar energy collector. A second fluid conduit extends from the outlet to the heat pump, and from the heat pump to the inlet, for transporting the heat exchange fluid, from the outlet to the inlet through the heat pump. A fluid pump is provide for urging the fluid to flow from the inlet to the outlet through the ground loop, and from the outlet to the inlet through at least one of the first and second conduits. Control valves and a controller may be provided to automatically select a fluid flow mode from a number of selectable modes.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This applications claims the benefits of related U.S. Provisional Application Ser. No. 60/776,225, filed Feb. 24, 2006, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to integrated thermal energy systems.

BACKGROUND OF THE INVENTION

Geothermal systems are useful for providing the energy needs of a building, such as heating, cooling and air conditioning. A typical geothermal system includes a geothermal heat pump, and a ground loop connected to heat pump. On the one hand, ground loop exchanges heat with the earth (either the ground or a large water body such as a lake), where the earth acts as both a heat source and a heat sink. On the other hand, ground loop supplies or removes heat from heat pump depending on its mode of operation. Thus, a geothermal system can efficiently utilize natural sources of energy, such as the thermal energy stored in the earth, and is environmentally friendly. However, a simple geothermal system is often not sufficient to meet the needs of the building it services.

Solar energy is another natural source of energy and solar energy systems have been combined with geothermal systems to supplement the energy supply. In conventional integrated solar and geothermal systems, both ground loop and the solar system are connected to heat pump so that they can simultaneously or individually provide heat to heat pump.

However, such conventional integrated systems have some drawbacks. One problem is that such integrated systems often require expensive and extensive additional equipment and control components, such as additional pumps, valves and the like. Further, efficiency of energy usage and storage in such systems can still be improved.

Accordingly, there is a need for an improved integrated thermal system. There is also a need for an integrated thermal system where the thermal energy resources are efficiently utilized. There is a further need for an integrated thermal system that is relatively inexpensive and simple.

SUMMARY OF THE INVENTION

In an aspect of the present invention, there is provided a thermal energy system that includes a solar energy collector, a ground loop having an inlet and an outlet, and a heat pump. A first fluid conduit extends from the outlet to the solar energy collector, and from the solar energy collector to the inlet, for transporting a heat exchange fluid, from the outlet to the inlet through the solar energy collector. A second fluid conduit extends from the outlet to the heat pump, and from the heat pump to the inlet, for transporting the heat exchange fluid, from the outlet to the inlet through the heat pump. A fluid pump is provide for urging the fluid to flow from the inlet to the outlet through the ground loop, and from the outlet to the inlet through at least one of the first and second conduits. Control valves and a controller may be provided to automatically select a fluid flow mode from a number of selectable modes. The mode selection may be made in response to detected temperatures in the conduits.

The selectable modes may include a first mode in which the fluid flows from the ground loop to the heat pump through the outlet and from the heat pump to the ground loop through the inlet; a second mode in which the fluid flows from the ground loop to the solar energy collector and from the heat pump to the ground loop through the inlet; and a third mode in which a portion of the fluid flows from the ground loop to the heat pump through the outlet and from the heat pump to the ground loop through the inlet, and a remaining portion of the fluid flows from the ground loop to the solar energy collector and from the heat pump to the ground loop through the inlet.

Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures, which illustrate, by way of example only, embodiments of the present invention,

FIG. 1 is a schematic diagram of a thermal energy system, exemplary of an embodiment of the present invention;

FIG. 2 is a schematic diagram of a specific embodiment of the thermal energy system of FIG. 1;

FIG. 3 is a schematic diagram of the control components of the system of FIG. 2; and

FIG. 4 is a schematic diagram of a variation of the thermal energy system of FIG. 2.

DETAILED DESCRIPTION

FIG. 1 shows an integrated thermal energy system 10, exemplary of an embodiment of the present invention. System 10 includes a heat pump 12 that provides heating/cooling, a ground loop 14, and a solar energy collector 16. Ground loop 14 has an inlet 18 and an outlet 20. A conduit 22 extends from in outlet 20 to heat pump 12 and from heat pump 12 back to inlet 18. A conduit 24 extends from outlet 20 to solar energy collector 16 and from solar energy collector 16 back to inlet 18. A fluid pump 26 is located in ground loop 14. A valve 28 is provided in conduit 22 and a valve 30 is provided in conduit 24.

Heat pump 12 may be any suitable heat pump and may be a conventional geothermal heat pump or ground source heat pump. For example, heat pump 12 may operate in two possible modes, a heating mode and a cooling mode, depending on demand. Heat pump 12 may also be turned off when no service is required. In the heating mode, thermal energy needs to be supplied to heat pump 12 such as by ground loop 14. In the cooling mode, thermal energy needs to be extracted from heat pump 12, and be transported away, such as to ground loop 14.

Ground loop 14 may be a conventional closed ground loop in a conventional geothermal energy system. A geothermal system is also referred to as a ground system or geo-exchange system. Ground loop 14 may include any fluid storage or transport device that is configured to store and transport a heat exchange fluid therein for storing or dissipating thermal energy. As is typical, ground loop 14 may be buried underground or placed deep in a large body of water, such as a lake, pond, or the like, so that the fluid can exchange heat with the earth. Suitable fluid storage devices include fluid pipes or tubes, such as plastic or metal pipes, and the like. Other suitable devices for ground loop 114 may also be possible, as can be understood by persons skilled in the art. When ground loop 14 is underground, inlet 18 and outlet 20 may or may not be located underground, and may be connected to the underground portion of ground loop 14 in any suitable manner.

The heat exchange fluid may be any suitable fluid. For example, a conventional fluid for conventional geothermal system may be used. In one embodiment, the fluid may include water and antifreeze. For example, the fluid may a mixture of ethanol and water, methanol and water, propylene glycol and water, or the like. To ensure proper operation, the fluid may be selected to suit the needs of each of heat pump, solar energy collector, and ground loop, as can be understood by persons skilled in the art.

Ground loop 114 (including any heat exchange fluid contained therein) has a sufficiently large apparent thermal capacitance so that it has a relatively stable temperature and can act both as a heat source and a heat sink for the geothermal system. Ground loop 14 can store and exchange heat from the earth depending on the system need. In one embodiment, ground loop 14 includes fluid pipelines that are buried underground, as in a conventional ground loop. Ground loop may be constructed using any conventional material for constructing ground loops. Ground loop 14 may have any suitable configuration, shape, structure and size. For example, ground loop 14 may be a horizontal ground loop or a vertical ground loop. However, due to the efficient use and transport of thermal energy that is possible in system 10, ground loop 14 may have a shortened overall length, as will become clear below.

Solar energy collector 16 may be any suitable solar energy collecting apparatus, and may include a conventional solar panel and the control components for a conventional solar panel system. Solar energy collector 16 may also include any suitable necessary or optional components for improving safety, performance or efficiency. For example, solar energy collector 16 may include a relief mechanism for protecting solar panel during cold weather conditions. For example, the relief mechanism may be activated when the temperature of the heat-exchange fluid in conduit 24 at solar energy collector 16 is higher than a pre-selected threshold temperature to prevent further heat transfer to the heat-exchange fluid at solar energy collector 16, particularly when there is no fluid flow in conduit 24. Optionally, solar energy collector 16 may be configured so that it can be operated in either an energy collecting mode or an energy dissipating mode, the benefit of which will become clear below.

A conduit 22 is provided for transporting the heat exchange fluid from outlet 20 to inlet 18 through heat pump 12. Another conduit 24 is provided for transporting the heat exchange fluid from outlet 20 to inlet 18 through solar energy collector 16. Conduits 22 and 24 may be made of any suitable material and may have any suitable size, shape and length, depending on the application. Conduits 22 and 24 may include conventional pipelines used in thermal energy systems, and may be made of the same or different materials.

Fluid pump 26 may be any suitable fluid pump, and may include a conventional fluid pump used in a geothermal system. As depicted, fluid pump 26 is located in ground loop 14 for urging the fluid to flow from inlet 18 to outlet 20 through ground loop 14, and from outlet 20 to inlet 18 through at least one of conduits 22 and 24. As can be understood, additional fluid pumps may be added for added fluid control or pumping power. However, as can be understood, a single pump is sufficient to urge the fluid to flow as described above. In different embodiments, particularly when more than one fluid pumps are provided, fluid pump 26 may be located outside ground loop 14, such as in either conduit 22 or 24. The optimal location and other properties of fluid pump 26 can be selected by one skilled in the art depending on the particular application. As depicted in FIG. 1, pump 26 urges the fluid to flow from inlet 18 to outlet 20 within ground loop 14. Pump 26 may be a one direction pump. As can be appreciated, in some situations, it may be desirable to be able to flow the fluid in both directions in ground loop 14. Thus, in a different embodiment, pump 26 may be capable of reversing its pumping direction. When the pumping direction is reversed, the inlet and outlet of ground loop will also switch role.

Each of valves 28 and 30 is configured and located to regulate the fluid flow in the respective conduit. In different embodiments, two or more valves may be provided in each conduit 22 or 24. The valves may include one or more of two way valves, gate valves, ball valves, relief valves, and the like.

Optionally, a controller 32 is provided for controlling the operation of fluid pump 26 and valves 28 and 30. Temperature sensors 34 and 36 are also provided for sensing temperatures in conduits 22 and 24 respectively. Further, as is typical in a conventional geothermal system, heat pump 12 may be coupled to a heat recovery ventilator (HRV) 38 in a heat exchange relationship for servicing a service area 40. A temperature sensor 42 may also be provided for monitoring a temperature in service area 40.

Controller 32 may be in communication with fluid pump 26, valves 28 and 30 for controlling the operation thereof. Controller 32 may also be in communication with temperature sensors 34 and 36 for receiving signals therefrom respectively, so that the operation of fluid pump 26 and valves 28 and 30 may be controlled in response to or based on the received signals. Optionally, controller may also receive signals from sensor 42 and controls the operation of heat pump, and other components of system 10. Controller 32 may include a computer system and software for automatic controlling the operations of various components of system 10. For example, controller 32 may be able to control valves 28 and 30 to selectively allow or prevent flow of the fluid in each of them, independent of one another.

Each of the sensors mentioned above may be a conventional sensor for sensing temperature and may include thermostats and other conventional temperature sensing and control devices used in temperature control systems. They can be readily selected and implemented by those skilled in the art.

Optionally, heat pump 12 or ground loop 14 may be connected with other heating/cooling components such as hot water tanks, heat exchangers, heating sources (not shown), or the like, as can be understood by persons skilled in the art. Also, additional control components and sensors, such as flow rate sensors (not shown), may be provided in one or more of ground loop 14 and conduits 22 and 24, the use of which will become clear below.

System 10 can be constructed relatively inexpensively, with standard components used in a conventional geothermal system and a conventional solar energy collector. It is not necessary to add complicated, or special, fluid control components that are not used in conventional geothermal systems. Yet, heat exchange within system 10 can still be efficient, as will be discussed below. In some cases, it is more efficient than a conventional thermal system where a heat exchange fluid flows directly between a heat pump (or heat exchanger) and a solar panel without first going through a ground loop. It is also not necessary to add additional, or separate, ground loops in order to take full advantage of the solar energy collector.

In operation, fluid pump 26 and valves 28 and 30 are operated, such as under the control of controller 32, to selectively urge the fluid to flow in system 10 in one of a plurality of selectable flow modes.

In a first flow mode, valve 28 is open and valve 30 is closed. When pump 26 is activated, it urges the fluid to flow from ground loop 14 to heat pump 12 through outlet 20 and from heat pump 12 to ground loop 14 through inlet 18. This mode may be selected, for example, when heat pump 12 is in operation, either in heating or cooling mode, but heat exchange between solar energy collector 16 and ground loop 14 is not needed or not desirable. It may not be desirable to exchange heat between solar energy collector 16 and ground loop 14 when the heat exchange would be in the wrong direction, as can be understood by person skilled in the art.

In a second flow mode, valve 28 is closed and valve 30 is open. When pump 26 is activated it urges the fluid to flow from ground loop 14 to solar energy collector 16 through outlet 20 and from solar energy collector 16 to ground loop 14 through inlet 18. This mode may be selected when heat pump 12 is in the off mode. As can be appreciated, in this mode, heat is continuously exchanged between solar energy collector 16 and ground loop 14. As a result, thermal energy can be continuously supplied to or extracted from ground loop 14 depending on the projected future thermal energy demand on system 10. For example, solar energy may be collected and converted to thermal energy at solar energy collector 16 and transported, by the fluid, to, and stored at, ground loop 14. On the other hand, when needed, thermal energy may be transported from ground loop 14 to, and dissipated at, solar energy collector 16. In the latter case, solar energy collector 16 may act as a heat radiator.

In a third flow mode, both valves 28 and 30 are open. When pump 26 is activated, it urges a portion of the fluid to flow from ground loop 14 to heat pump 12 through outlet 20 and from heat pump 12 back to ground loop 14 through inlet 18, and urges a remaining portion to flow from ground loop 14 to solar energy collector 16 through outlet 20 and from solar energy collector 16 back to ground loop 14 through inlet 18. Thus, heat is exchanged between heat pump 12 and ground loop 14, and between ground loop 14 and solar energy collector 16, respectively. In this mode, the heat exchange fluid flows between heat pump 12 and solar energy collector 16 only through ground loop 14 in both supply and return direction.

In a fourth mode, fluid pump 26 may be turned off, or both valves 28 and 30 may be closed, so that no fluid will flow between ground loop 14 and any one of conduits 22 and 24. and

Other flow modes may also be possible. For example, fluid flow rate may be selectively increased or decreased in one or both of conduits 22 and 24, such as under selective regulation of valves 28 or 30. In another example, additional fluid flow loops may be connected to ground loop 14 or conduits 22 and 24, for allowing the fluid to flow in different flow paths.

During use, heat pump 12 and HRV 38 may be operated as in a conventional heating/cooling, ventilation and air conditioning (HVAC) system. In particular, HRV 38 may provide heating or cooling air to service area 40, based the need at the time. Heat pump 12 can operate in either a heating mode or a cooling mode, as is typical in conventional operation, and exchanges heat with HRV 38 to either supply or extract heat from HRV 38 depending on the operating mode of HRV 38.

When heat pump 12 is in operation, valve 28 is typically open, and fluid pump 26 urges the heat exchange fluid to flow in conduit 22. Thus, heat pump 12 also exchanges heat with the fluid flowing in conduit 22. When heat pump 12 is operating in the heating mode, heat is transferred from ground loop 14 to heat pump 12 by the fluid. When heat pump 12 is operating in the cooling mode, heat is transferred from heat pump 12 to ground loop 14. When heat pump 12 is not in operation, valve 28 may be closed so that no fluid will flow through conduit 22.

Independently, when solar energy collector 16 is irradiated by solar radiation, solar energy may be collected and converted to thermal energy. When valve 30 is open, pump 26 can urge the heat exchange fluid to flow in conduit 24. When the temperature of the input fluid at solar energy collector is low, thermal energy may be transferred to the fluid at solar energy collector 16 and transported to ground loop 14 by the fluid through conduit 24 and inlet 18. On the other hand, when no solar radiation is available or when the input fluid at solar energy collector 16 is high, heat may be transferred from ground loop 14 to solar energy collector 16 and may be dissipated there. That is, a solar panel may be used a radiator for dissipating heat in this case. When transfer of thermal energy to or from solar energy collector is not needed or not possible, valve 30 may be closed so that no fluid will flow through conduit 24.

As can be appreciated, transfer of thermal energy through each of conduits 22 and 24 can be effected or stopped independent of each other. Thus, more flexible and efficient control may be achieved using system 10.

In particular, when solar energy is available, valve 30 may be open so that energy may be continuously transferred to ground loop 14 from solar energy collection 16, regardless of whether heat pump 12 is in operation or its mode of operation. On the one hand, as solar energy collector 16 always receives fluid from the output end (outlet 20) of ground loop, which typically has a relatively stable low temperature, the heat transfer efficiency at solar energy collector 16 may be maintained at a relatively high level regardless of the operating mode of heat pump 12. On the other hand, as ground loop always receives fluid directly from solar energy collector 16, thermal energy collected from solar energy collector 16 is also relatively efficiently transferred to ground loop 16.

Therefore, regardless of the operating mode of heat pump 12, thermal energy can be continuously collected at solar energy collector 16 and transferred to ground loop 14, with high efficiency and without adversely affecting the operation of heat pump 12.

Further, when it is desirable to lower the temperature in ground loop 14, valve 30 may again be open and solar energy collector 16 may be set into the energy dissipating mode so that thermal energy may be dissipated at solar collector 16.

When desired, it is also possible to adjust or select the operation mode of solar energy collector 16 based on the operation mode of heat pump 12 and the temperature in ground loop 14, as can be understood by persons skilled in the art.

The selection of the operation modes, fluid flow modes, and the operation of pump 26 and valves 28 and 30 may be controlled and effected automatically by controller 32, such as based on the sensed temperatures at various sensors 34, 36, and 42, and other information including stored system history or performance data and detected flow rate (when such sensors are provided). For instance, controller 32 may select or reset the optimal fluid flow mode in response to a detected signal received from temperature sensor 34 or another sensor. Such a control system may be implemented through hardware, or software or a combination of both by persons skilled in the art.

As the energy sources are more efficiently managed, the total length (or thermal capacity) of ground loop piping can be significantly reduced, e.g. by about 20% in some cases.

A specific exemplary embodiment of the present invention is illustrated in FIG. 2, which shows an integrated thermal energy system 100 for a building such as a residential building.

System 100 includes two subsystems: a solar thermal system 102 and a geothermal system 104. Pipelines 106 are provided to interconnect them and other various components of system 100. System 100 has a flow control center 108 for controlling fluid flow in the system.

Solar thermal system 102 includes a number of solar panels 116 for collecting solar energy and converting solar energy to thermal energy. Solar panels may be any conventional solar panels. A heat exchange fluid flowing in pipelines 106 goes through solar panel 116 for exchanging thermal energy with solar panel 116 and for transporting thermal energy to ground loop 114.

The geothermal system 104 may be a conventional geothermal system with the exceptions discussed below. As is typical, it includes one or more ground source heat pumps, also called geothermal heat pumps. In FIG. 2, only one heat pump 112 is shown, but more heat pumps may be provided. Heat pump 112 may be a water-to-air heat pump, such as a ZP048 or ZP060 pump manufactured by Essential Innovations™. Heat pump 112 may have a de-superheater (not shown). Heat pump 112 exchanges heat with a heat recovery ventilator (HRV) 138. HRV 138 may be a NU165 ventilator manufactured by NU-Air™. In the heating mode, heat pump provides thermal energy to the serviced component such as HRV 138, and extracts thermal energy from the pipeline coupled to it. In the cooling mode, heat pump extracts thermal energy from the serviced component, and dissipates thermal energy into the pipeline.

As illustrated, geothermal system 104 also includes a ground loop 114 formed by a portion 110 of pipelines 106. Ground loop 114 has an inlet 118 and an outlet 120.

A portion 122 of pipelines 106 extends from outlet 120 to inlet 118 through heat pump 112, which includes a supply conduit 122 A and a return conduit 122B. A portion 124 of pipelines 106 extends from outlet 120 to inlet 118 through solar panel 116, which includes a supply conduit 124A and a return conduit 124B.

Various thermal and fluid components are disposed along, and coupled to, the pipelines 106 to perform various functions as can be understood by persons skilled in the art.

Typically, as illustrated, geothermal system 104 includes one or more fluid pumps for urging and regulating fluid flow within the pipelines 106. As depicted, two fluid pumps 126A and 126B are located at the flow control center 108. Each fluid pump may be a BGM-3655 pump manufactured by Flow Center™.

One or more valves or gates may be disposed along pipelines 106 for controlling the flow direction and the flow rate of a heat-exchange fluid.

For example, a set of ball valves 128A and 128B may be provided in conduits 122A and 122B respectively for regulating fluid flow in pipeline portion 122. A set of valves 130A, 130B and 130C may be provided in conduits 124A and 124B for regulating fluid flow in pipeline portion 124. Valve 130A is a two-way electric valve. The electric valve 130A may be an on-off valve controlled by control system 132, as will be further discussed below. Valve 130B is a gate valve. Valve 130C is a circuit setter. As shown in FIG. 2, valves 130A and 130B are provided in the return conduit 124B from solar panel 116, and valve 130C is provided in the supply conduit 124A.

System 100 may have one or more energy or fluid storages or supplies, and the like. A thermal energy storage may be a fluid tank, such as a water tank. In FIG. 2, three tanks are shown, a cold water supply tank 150, a hot water tank 152, and an expansion tank 154. Tanks 150 and 152 are connected to heat pump 112 for extracting heat therefrom. For example, the hot water tank 152 may be a DEN-66 tank manufactured by A.O. Smith™. The expansion tank 154 may be a AST-5 tank manufactured by AMTROL™. The primary function of the expansion tank 154 is for pressure management in pipelines 106, as can be understood by persons skilled in the art. The pipelines 106 themselves with the fluid in them may serve as a thermal storage, although the primary function of the fluid is to transport and transfer heat. In this regard, the pipelines 106, or pipeline portion 110, may have a total length designed to provide sufficient thermal energy storage capacity. The pipelines 106 may also include one or more sections, such as ground loop 114, specifically configured for storing thermal energy. It may be advantageous to locate a thermal storage underground, as can be understood by persons skilled in the art.

Each fluid storage may supply fluid to or extract fluid from a fluid supply. Each energy storage or heat-exchange unit may supply thermal energy to or extract thermal energy from a serviced area in the building. For example, the water tanks 150 and 152 may be connected to a domestic hot water supply (not shown) and a domestic cold water supply (not shown).

A heat-exchange unit such as heat pump 112 may exchange thermal energy with an air supply (such as HRV 138) for the building, such as to provide air-conditioning within the building. The pipelines 106 may be connected using typical piping connectors and components including strainers such as strainer 156, PT plugs 158, and the like. Ground loop 114 may also include one or more drain lines (not shown). Solar panel 116 may include a relief mechanism (not shown) for protecting solar panel 116 during cold weather conditions or when the fluid in conduit 124A becomes too cold.

Various sensors and detectors may be provided and disposed in the system 100 for providing input data to control system 132. For example, a temperature sensor 134 may be provided in the return conduit 124B near solar panels 116 for monitoring the temperature of the return fluid from solar panels 116. A thermostat 142 may be provided to control the operation of heat pump 112 in response to temperature changes at a serviced location. Another temperature sensor 160 may be provided to monitor the outdoor air temperature.

An automatic control system 132, such as a computer system or any suitable controller, may be integrated with system 100 for controlling the operation of system 100, as illustrated in FIGS. 2 and 3. For example, control system 132 may be provided on a control panel or board (not shown) located at or near heat-pump 112. A portion of control system 132, such as remote controller 162, may be located remotely from ground loop 114 or from the building that is being serviced. Remote controller 162 may communicate with control system 132 through wired or wireless communication. Wired or wireless communication may also be used to communicate input data and operation command signals to and from control system 132. For example, control system 132 may include a modem (not shown) for communicating with remote controller 162 through a telephone line (not shown). For simplicity, the electronic communication connections between control system 132 and some of the control components such as pumps 126A and 126B and valve 130A, are not expressly depicted in FIG. 2. However, it should be understood that such connections, when needed, are provided, as illustrated in FIG. 3.

In the embodiment depicted in FIGS. 2 and 3, it is assumed that control system 132 is located at or near heat pump 112, which may be housed on a control board (not shown). Further, it is assumed that thermostat 142 is provided for sensing the temperature at the serviced location and for activating heating/cooling service to the serviced location, and a solar panel controller 164 is provided at solar panel 116 for controlling the operation of solar panel 116. Solar panel controller 164 may be a differential temperature controller, and may receive input data from solar panel temperature sensor 134 and, optionally, control the operation of valve 130A. Control system 132 can receive input data/signal from sensors 134 and 160, either directly, or indirectly through solar panel controller 164 and thermostat 142 respectively as shown. Control system 132 may communicate with flow center 108, and controls the operation of fluid pumps 126A and 126B and valve 130A.

In use, thermostat 142 for the serviced location is pre-set to a set point, indicating that cooling is required when the temperature at the location is below the set point and heating is required when the temperature is above the set point.

When heating is required, such as when triggered by thermostat 142, heat pump 112 is turned on and operates in the heating mode. Thus, thermal energy is provided to the location being serviced to increase the temperature at the location. Fluid pumps 126A and 126B are also on so that the heat-exchange fluid flows within ground loop 114 and pipeline portion 122 to provide thermal energy to heat pump 112.

When cooling is required, such as when triggered by thermostat 142, heat pump 112 is also turned on but operates in the cooling mode. Thus, cooling air is provided to the location being serviced to decrease the temperature at the location. At the same time, thermal energy needs to be dissipated from heat pump 112. Thus, pumps 126A and 126B at center 108 are again turned on to keep fluid flowing in pipeline portions 110 and 122, such that thermal energy can be more efficiently removed from heat pump 112.

During use, regardless of whether heat pump 112 is on, or whether it is in the cooling or heating mode, valve 130A may be normally open, such that the heat-exchange fluid may flow through both ground loop 114 and pipeline portion 124. It is assumed gate valve 130B is normally open. When valve 130A is open, the solar energy source is activated. When the fluid temperature in ground loop 114 is low, thermal energy may be continuously collected from solar panel 116 and transferred to and stored in ground loop 114. When the fluid temperature in ground loop 114 is high, thermal energy may be dissipated when the fluid flows through pipeline portion 124.

Valve 130A may also be selectively closed depending on the situation. The open/closed state of valve 130A may be controlled by a controller such as a controller (not shown) at control system 132, or by both control system 132 and solar panel controller 164. For example, valve 130A may be controlled as follows in an exemplary embodiment of the present invention.

The temperature detected at sensor 134 is denoted herein as Ts, which is the temperature of the output fluid from solar panel 116. The temperature of the output fluid from ground loop 114 is denoted Tg, which may be detected with a temperature sensor (not shown) which monitors the temperature in conduit 122A at heat pump 112 and may be a part of heat pump 112. The outdoor air temperature detected at sensor 160 is denoted Ta.

While heat pump 112 operates in the heating mode, or is off or otherwise inactive, valve 130A may be kept open when Ts>Tg, and closed when Ts<Tg. However, while heat pump 112 operates in the cooling mode, valve 130A may be closed when Ts>Tg, and open when Ts<Tg. The above open/close states of value 130A are summarized in Table 1.

TABLE I
State of Valve 130A
	Heat Pump mode	Heating/Off	Cooling
	Ts < Tg	Close	Open
	Ts > Tg	Open	Close

Further, valve 130A may be toggled, i.e. alternatively opened and closed, periodically. For example, it may be opened for 1 to 10 minutes per hour, when Ta is below a threshold temperature, such as −10° C., to prevent the heat-exchange fluid in pipe portion 124 from freezing under cold weather conditions, particularly when no fluid circulation was otherwise required in pipe portion 124.

Whenever valve 130A is open, pumps 126A and 126B are kept on to urge the fluid flow in pipeline portions 110 and 124. Pumps 126A and 126B are also kept on when valves in conduits 122 are open.

Fluid pumps 126A and 126B may be controlled by control system 132. Pumps 126A and 126B may be turned on whenever heat pump 112 is on or when 130A is open. Pumps 126A and 126B can receive a signal indicative of the open status of valve 130A from control system 132, which may in turn receive a status signal from an end relay switch (not shown) at valve 130A.

The temperature set point for hot water tank 152 may be 120° F. The electric heating element (not shown) of tank 152 may be set to maintain a tank temperature 10° F. below the set point, i.e., 110° F. The de-superheater (not shown) of heat pump 112 may be used to maintain the tank temperature at the set point.

As can be appreciated, thermal energy can be extracted from or injected into ground loop 114. The energy exchange between the heat-exchange fluid in ground loop 114 and heat pump 112 can be monitored by detecting the temperature difference in conduits 122A and 122B near or at heat pump 112. Temperature sensors (not shown) may be placed either inside or just outside heat pump 112 for this purpose. For example, assuming the temperature difference is ΔT, then the energy transferred (ΔT) can be calculated as: ΔE =k c ΔT, where k is the flow rate and c is the fluid specific heat capacity constant. Energy consumption can be monitored with an analogue totalizer at control system 132.

The heat-exchange fluid can be water. The water flow rate through heat pump 112 can be calculated as the product of the initial pressure drop through heat pump 112 and a system temperature constant, as can be appreciated by a person skilled in the art. The system temperature constant can be dependent on the input water temperature to thermal system 100, such as from the domestic cold water supply. The initial pressure drop may be measured at installation and stored in control system 132, such as at a memory therein.

The power consumption by heat pump 112 can be monitored using an analogue totalizer (not shown). This information may be used to access the efficiency of the system.

A variation of the embodiment of FIG. 2 is shown in FIG. 4, where the system 100′ is similar to system 100 with the exceptions that can be seen in the figures. For example and notably, ball valves 128A/128B, strainer 156, and water tank 150 are omitted in system 100′. System 100′ can be operated in a similar manner as for system 100 with some modifications which will be apparent to those skilled in the art. Systems 100 and 100′ may serve different building needs for heating and cooling, as can be appreciated by persons skilled in the art.

Embodiments of the present invention may be used in any buildings or structures that require heating/cooling, including residential homes such as single homes and multi-dwelling units.

As now can be appreciated, the above exemplary embodiments have certain advantages. First, the overall system efficiency is increased by integrating the solar system 102 with the geothermal system 104. By controlling the fluid flow, depending on the thermal consumption requirement and the conditions of the two heat sources, more efficient use of each source can be achieved. For example, solar panel 116 may be used as a heat radiator, when cooling is required in the building, instead of as a heat source. Further, thermal energy collected from solar panel 116 can be more efficiently stored and transported using ground loop 114. With a combined system, ground loop pipelines may be shortened as the same heat storing capacity may be achieved with a shorter pipeline when the fluid temperature is increased, due to the thermal energy collected and transferred from solar panel 116. On the other hand, the solar system 102 may operate more efficiently when the input fluid has a lower temperature such as due to heat exchange in ground loop. Further, the automatic control provided by control system 132 makes it convenient to operate system 100 or 100′ efficiently.

As now can be understood, modifications can be made to the systems 10 or 100/100′. For example, in different embodiments, additional sensors can be provided at various locations in the system to provide additional temperature or flow rate information.

In embodiments of integrated thermal systems, such as systems 10, 100/100′, it is possible to use fewer or less expensive equipments, as compared to conventional integrated thermal systems. For example, the circulation of the heat exchange fluid in system 10 may be effected using a single fluid pump, such as pump 26, in all flow modes. It is not necessary to use multiple fluid pumps for different flow modes. In system 10, it is also not necessary to use expensive, complicated, or non-standard components or equipments which are not normally used in typical geothermal systems. As standard components or equipments can be used, it may be relatively easy and inexpensive to construct and install an embodiment of the present invention. It is also relatively easy and inexpensive to modify an existing thermal system according to aspects of the present invention.

Other features, benefits and advantages of the embodiments described herein not expressly mentioned above can be understood from this description and the drawings by those skilled in the art.

The contents of each reference cited above are hereby incorporated herein by reference.

Of course, the above described embodiments are intended to be illustrative only and in no way limiting. The described embodiments are susceptible to many modifications of form, arrangement of parts, details and order of operation. The invention, rather, is intended to encompass all such modification within its scope, as defined by the claims.

Claims

1. A thermal energy system comprising:

a solar energy collector;

a ground loop having an inlet and an outlet;

a heat pump;

a first fluid conduit extending from said outlet to said solar energy collector, and from said solar energy collector to said inlet, for transporting a heat exchange fluid, from said outlet to said inlet through said solar energy collector;

a second fluid conduit extending from said outlet to said heat pump, and from said heat pump to said inlet, for transporting said heat exchange fluid, from said outlet to said inlet through said heat pump; and

a fluid pump, for urging said fluid to flow from said inlet to said outlet through said ground loop, and from said outlet to said inlet through at least one of said first and second conduits.

2. The thermal energy system of claim 1, wherein said fluid pump is located in said ground loop.

3. The thermal energy system of claim 2, wherein said fluid pump consists of a single pump.

4. The thermal energy system of claim 1, comprising a first valve for regulating flow of said fluid in said first conduit and a second valve for regulating flow of said fluid in said second conduit.

5. The thermal energy system of claim 4, comprising a controller for controlling operation of said fluid pump and said first and second valves.

6. The thermal energy system of claim 5, wherein said first and second valves comprises a valve selected from a two way valve, a gate valve, a ball valve, a relief valve, and a circuit setter.

7. The thermal energy system of claim 6, comprising a first temperature sensor for sensing a temperature in said first conduit, and a second temperature sensor for sensing a temperature in said second conduit.

8. The thermal energy system of claim 7, wherein said controller is in communication with each one of said first and second temperature sensors for receiving a temperature signal from each one of said first and second temperature sensors, said controller controlling operation of said fluid pump and said first and second valves in response to receiving said temperature signals.

9. The thermal energy system of claim 8, wherein said controller controls said first and second valves to selectively allow or prevent flow of said fluid in each one of said first and second conduits.

10. The thermal energy system of claim 5, wherein said controller is adapted to control said fluid pump and said first and second valves to selectively urge said fluid to flow in one of a plurality of selectable modes, said selectable modes comprising

a first mode in which a portion of said fluid flows from said ground loop to said heat pump through said outlet and from said heat pump to said ground loop through said inlet, and a remaining portion of said fluid flows from said ground loop to said solar energy collector and from said heat pump to said ground loop through said inlet; and

a second mode in which said fluid flows from said ground loop to said solar energy collector and from said heat pump to said ground loop through said inlet.

11. The thermal energy system of claim 10, wherein said selectable modes comprise a third mode in which said fluid flows from said ground loop to said heat pump through said outlet and from said heat pump to said ground loop through said inlet.

12. The thermal energy system of claim 10, wherein said controller is adapted to receive a first signal indicative of a first temperature in said first conduit and a second signal indicative of a second temperature in said second conduit, and to select said one of said modes in response to receiving said first and second signals.

13. The thermal energy system of claim 12, wherein said controller is adapted to select said one of said modes based on a difference between said first and second temperatures and whether said heating pump is operating in a heating mode or a cooling mode.

14. The thermal energy system of claim 10, wherein said controller is adapted to select one of said modes automatically.

15. The thermal energy system of claim 5, wherein said controller is adapted to control said fluid pump and said first and second valves to selectively decrease or increase a flow rate of said fluid in at least one of said ground loop and said first and second conduits.

16. The thermal energy system of claim 1, wherein said heat exchange fluid comprises water and an anti-freeze.

17. The thermal energy system of claim 1, wherein said heat exchange fluid comprises water and at least one of ethanol, methanol, and propylene glycol.

18. The thermal energy system of claim 1, wherein said solar energy collector comprises a relief mechanism for preventing heat transfer to said heat-exchange fluid when said heat-exchange fluid in said first conduit has a temperature higher than a threshold temperature.

19. The thermal energy system of claim 1, wherein said heat pump is coupled to a heat recovery ventilator in heat exchange relationship.