Patent Application
20070235179
This invention relates generally to heating and cooling systems for structures such as homes and buildings, etc. and more specifically to such structures utilizing a heating and cooling system that utilize a heat pump in which heat within the structures is used to support the heat pump, thus recycling energy that otherwise would escape from the structure.
Heating and cooling systems that utilize a buried ground coil through which a medium passes for heating by earthen material are typically called “geothermal systems.” Briefly described, geothermal heating and cooling systems circulate a fluid heating medium through coils of tubing that are buried in the ground or immersed in a pond. The earth acts as a source of heat; the fluid is heated as it is circulated through the coils in the ground and is then pressurized prior to flowing through a heat exchanger such as a heat pump, which may be of the liquid-to-air type or liquid-to-liquid type. The heat derived in the heat pump from the relatively warmed fluid is used to heat a structure. The fluid, cooled by passage through the heat exchanger, is directed back to the buried ground coil where it is again warmed by the heat retained in the earth.
There are of course many variations on this basic theme. Some geothermal systems are of the “closed” type, where the loops that circulate the heating medium are in a fully close loop that is buried in the ground. Other systems are “open.” In an open loop system, ground water is pumped through a geothermal heat pump where heat is drawn off the liquid. The relatively cooled water is then discharged into a pond. As noted above, a “geothermal” system may also contemplate immersion of the coils in a pond. In this sense, a body of water also acts as a heat source that may be utilized to warm the medium that flows through the coils.
In addition to geothermal heating and cooling systems, conventional electric heat pumps are used ubiquitously because all of these kinds of units help make usage of energy more efficient. Nonetheless, as energy resources become more scarce, and as demand for energy increases, there is a substantial need for heating and cooling systems that use energy more efficiently. As a corollary, as energy becomes more expensive the demand for energy-efficient heating and cooling systems increases as a matter of economics: the less energy that is used, the less the cost of purchasing the energy.
There is a significant need therefore for efficient heating and cooling systems for homes and buildings.
The present invention is an improved method and apparatus for efficiently heating and cooling a structure such as a residence, commercial building, etc. The system utilizes a closed loop system similar to a closed loop geothermal heating system but locates the coils in the system to the interior of the structure in a location where the coils are able to be heated by relatively warm air that is used to heat the building. The structure may utilize an optional heating system such as a geothermal heating system, furnace or a conventional electric heat pump. The closed loop system that is located in the interior of the structure is configured to capture heat from the interior of the structure and use that heat to warm the heating medium in the coils.
With reference to
Individual components of heating and cooling system 10 will be described beginning with furnace 14. The furnace used with the present invention may be any kind, including conventional forced air gas-fired or electric furnaces, and other “furnace” types including radiant floor heating. The purpose of furnace 14 is to provide heat and cooling to structure 12. Accordingly, it will be appreciated that the term “furnace” is used generically herein to describe any heat source for heating and cooling structure 12. Nonetheless, the furnace 14 illustrated herein is conventional and is under the control of a thermostat 26 that regulates operation of the furnace, and which typically is located in a convenient place in structure 12. Different thermostat configurations may be used, for example, thermostats that rely upon various zones. The furnace illustrated herein includes conventional ducting 28 and a fan shown schematically at 29 that delivers heated (and cooled) air to the interior of the structure, and as shown in
Geothermal heat pump 16 also is a conventional unit that essentially functions as a medium-to-air heat exchanger where heat carried into the heat pump from one of the source loops (i.e., either the structure source loop 20 or the ground source loop 18) is drawn off in the heat pump and transferred into the forced air conduit system of furnace 14 so that the heat may be used to warm structure 12. The geothermal heat pump 16 may be of any known type, such as an air-to-water heat pump, or a water-to-water type. With reference to
As noted, ground source loop 18 should be considered optional in the present invention. Generally described, a ground source loop system relies upon the relative temperature of the ground to heat or cool a heat exchange fluid flowing through coils that are buried in the ground. As relatively cool fluid flows from the cool side of the system and is circulated through the coils, the fluid is either warmed or cooled by the ground. The relatively warmed or cooled fluid is drawn off or extracted in a heat pump, which functions as a heat exchanger, to supply warm air or cool air, as the case may be, to structure.
The ground source loop 18 shown in the figures comprises a length of conduit or tubing defined as ground loop coils 32 which are buried in the ground at an appropriate depth. The ground loop coils 32 could just as well be submersed in a pond. A horizontal ground loop system is illustrated in
The structure source loop 20 according to the present invention is similar to the ground source loop 18 but is located in a different location and derives heat from different sources. Structure source loop 20 is connected to geothermal heat pump 16 through controller 22 and, assuming that structure 12 includes a ground source loop 18, defines a second heat exchange system used in structure 12. The structure source loop 20 illustrated in
Returning to
It will be appreciated that there are numerous equivalent manners in which the tubing 46 of structure source loop 20 may be installed above the winter-heated space 48, and further that the length of tubing used in any particular installation, including the length of tubing installed above the heated space, will vary. Preferably, the length of tubing installed above the heated space provides substantial surface area for exchange of heat from the warm air in the structure to the heat exchange fluid flowing through the conduit. With reference to
Regardless of the particular manner in which the coils of structure source loop 20 are installed, insulation is used between the tubing and the roof to ensure that the loop 20 is exposed to the interior of the structure but is insulated from cold air above the insulation and the exterior of the structure.
With reference now to
On the other hand, when ground source loop 18 is selected, microprocessor 62 operates valves 58 and 60 to define a flow path from warm side 36 through valve 58 and through warm side tubing 66 to heat pump 16. The cooled fluid is routed through cool side tubing 68 through valve 60 into cool side 34 of the ground source loop. It will be appreciated by those of ordinary skill in the art that one or more pumps are required as means to control flow of fluid through the structure source loop and ground source loop, and that the pumps are also under the control of microprocessor 62. Pumps 59 and 61 are shown schematically in
Operation of the heating and cooling system 10 will now be detailed in a first preferred embodiment in which a structure source loop 20 is used in structure 12, but a ground source loop 18 is not used. It should be understood that the invention described herein relates primarily to the structure source loop 20. The structure source loop 20 may be combined with a ground source loop 18 as described, but the ground source loop is optional. Thermostat 26 serves as the primary user interface for control of the system. When thermostat 26 determines that the temperature of the winter-heated space 48 is below a predetermined minimum temperature, or for example when the temperature on the thermostat is increased, the thermostat queries a ceiling temperature sensor 70 that is located above the winter-heated space 48 and measures the air temperature at the sensor. In
It will be appreciated that the structure source loop 20 will be used primarily in the winter months as a means of recovering heat from the warmed interior of a building. However, structure source loop 20 may be used for cooling as well. Consider for example a circumstance where the air temperature outside of structure 12 is relatively high, as in summer months, and the temperature at sensor 70 is lower than the temperature that is entered into thermostat 26. In such instances the structure source loop may be operated so that air that is at a temperature lower than that entered into the thermostat is circulated in the structure. Structure source loop 20 thus defines a method of recovering heat that is generated in a structure, and re-using that heat to warm the structure.
If heating and cooling system 10 includes a ground source loop 18 and a structure source loop 20, microprocessor 62 is preprogrammed to select either the ground source loop 18 or the structure source loop 20 depending upon which loop will provide the most efficient heat exchange. As shown in
Operation of the ground source loop 18 is identical to operation of the structure source loop 20 described above. Thus, when thermostat 26 determines that the temperature of the winter-heated space is below a predetermined minimum temperature, or when a specific temperature is entered into the thermostat, the thermostat queries both ceiling temperature sensor 70 and ground temperature sensor 72. Temperature data from sensors 70 and 72 is communicated to microprocessor 62 and the temperature data are compared to temperature data measured at thermostat 26. Microprocessor compares temperature data from sensors 70 and 72 and determines whether heat may be recovered from one of the loops (i.e., either structure source loop 20 or ground source loop 18), and if so, which loop will provide the most efficient heat exchange. In this example, assuming that microprocessor 62 compares temperature data from sensors 70 and 72 and determines that more heat may be recovered from ground source loop 18, microprocessor 62 operates valves 58 and 60 to select the ground source loop and fluid flow through the ground source loop is initiated. Geothermal heat pump 16 is operated either alone or in conjunction with furnace 14 to direct warm air into the winter-heated space 48 through ducting 28. As with the structure source loop 20, depending upon the difference between the temperature at ground temperature sensor 72 and thermostat 26, operation of the ground source loop 18 may be delayed while furnace 14 is operated by itself to raise the temperature of the winter-heated space 48 until the temperature difference between the two points meets a predetermined level where it operation of the ground source loop 18 is determined to meet predetermined efficiency criteria programmed in the microprocessor. And as noted earlier, the furnace may be operated with the furnace fan only, in which case heat drawn off the warm side of the ground source loop is used to heat structure 12. In other instances the heating system in furnace 14 may be operated simultaneously with geothermal heat pump 16 to heat structure 12.
When the temperature at thermostat 26 reaches the predetermined level microprocessor 62 controls and operates furnace 14, geothermal heat pump 16 and a selected loop 18 or 20 to maintain the desired temperature (as measured at thermostat 26). Thus, in a structure 12 that includes both a structure source loop 20 and a ground source loop 18, the microprocessor continuously queries temperature sensors 70 and 72, compares temperature data to determine which loop would be most efficient, and operates the heating and cooling system 10 accordingly.
Typically, a ground source loop 18 is relied upon more in the summer months with a structure 10 that includes a structure source loop 20. An example illustrates the foregoing. Assume that the temperature in the interior of structure 12 is 65° F. and an occupant sets thermostat 26 to 72° F. Thermostat 26 communicates that data to microprocessor 62. In this example, assume further that the temperature measured at sensor 70 is 78° F., and that the temperature measured at sensor 72 is 55° F. Microprocessor 62 compares these data from sensors 70 and 72 and because the temperature at sensor 72 is below the temperature entered into thermostat 26, will not select ground source loop 18. On the other hand, the temperature at sensor 70 for structure source loop 20 is greater than the temperature entered into the thermostat. Accordingly, if the difference between the temperature at sensor 70 and the temperature entered into thermostat 26 is greater than a preset minimum difference programmed into microprocessor 62, the microprocessor will initiate selection and operation of the structure source loop as described above. The preset minimum temperature difference programmed into microprocessor 62 for initiation of one of the heating and cooling loops is determined by many factors, including the efficiency of the system, the local climate, etc. and may be varied as necessary in any particular installation. In a different example, if the difference between the temperature at the thermostat and the temperature at sensor 72 exceeds a predetermined minimum, and the temperature at sensor 72 is greater than the temperature at sensor 70, then the controller will select the ground source loop 18 and will initiate operation of that loop.
It will be appreciated that the heating and cooling system 10 operates in a like manner when cooling of the structure is desired.
It will further be appreciated that various equivalent heating and cooling systems may be made by modifying the foregoing described embodiments. For example, the tubing 46 of structure source loop 20 may be replaced by a membrane-like sheet having fluid channels formed therein, where the membrane is installed between the heated interior space 48 insulation 56. Those of ordinary skill in the art will understand that other similar modifications will result in an equivalent apparatus for recovering heat from the interior of the structure via heat exchange fluid flowing above the heated interior space.
Having here described illustrated embodiments of the invention, it is anticipated that other modifications may be made thereto within the scope of the invention by those of ordinary skill in the art. It will thus be appreciated and understood that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.
