Patent Grant
7040108
Heat pumps and solar panels are two types of thermal energy systems, both of which have shortcomings. For example, heat pumps generally are nonfunctional below approximately 20° F., and thus are less practical in colder climates. Solar panels are dependent upon the sun's rays, and therefore do not function at night or on cloudy days. The number of hours and days of sunlight in the particular geographic region are major factors in the usefulness of solar panels.
Some prior art solar panels had water in the panel pipes and utilized large arrays to capture thermal energy from solar radiation for heating the water. A large surface area was required to adequately heat the water. Such systems were impractical in climates having temperatures low enough to freeze the water.
Other prior art solar panel systems attempted to utilize refrigerant gasses in place of water in the solar panels. However, these refrigerant systems were subject to failure due to excessive pressure created by rapid temperature increases in the panels when the panels were exposed to direct sunlight. This rapid temperature and pressure increase often led to failure of the tubing in the panel arrays, and premature failure of the refrigerant compressor. The tubing of the solar panel rays usually was made of soft copper, which is easy to bend and solder. Eventually, such solar panel systems using the refrigerant fluid was dropped due to the failure in the ability to control the rapid changes in the refrigerant gas pressures.
Accordingly, a primary objective of the present invention is the provision of an improved method and means for recovery of thermal energy from an ambient environment.
Another objective of the present invention is the provision of a method and means of thermal energy recovery wherein ambient thermal energy is absorbed in evaporator plates remote from the other components of the system.
Another objective of the present invention is the provision of a method and means for thermal energy recovery using reverse refrigeration technology.
Another objective of the present invention is the provision of a system for recycling thermal energy from ambient air to heat water.
Yet another objective of the present invention is the provision of a thermal energy recycling method wherein ambient thermal energy is absorbed by a refrigerant fluid, which is then compressed and passed through a heat exchanger to transfer thermal energy from the fluid to water, thereby heating the water.
Another objective of the present invention is the provision of a method of thermal energy recovery using an outdoor evaporator plate assembly, and an indoor compressor and heat exchanger.
A further objective of the present invention is the provision of a method and means of thermal energy recovery which functions 24 hours per day.
Yet another objective of the present invention is the provision of a method and means of thermal energy recovery which is not dependent upon direct exposure to solar rays.
Still another objective of the present invention is the provision of a method and means of thermal energy recovery and recycling which is functional down to temperatures of approximately −40° F.
Another objective of the present invention is a system for recovering and recycling thermal energy from an ambient environment, having unused thermal energy.
A further objective of the present invention is the provision of a method and means for thermal energy recovery which is economical to manufacture and install, and durable and efficient in use.
These and other objectives will become apparent from the following description of the invention.
The thermal energy recovery system of the present invention includes an evaporator plate assembly in an ambient environment, such as outdoor air. A compressor and heat exchanger are located indoors, remote from the evaporator plate assembly. A refrigerant fluid circulates through lines connecting the evaporator plate assembly, compressor and heat exchanger. Water circulates through lines connecting the heat exchanger to a hot water storage tank.
In the method of thermal energy recovery, the refrigerant fluid absorbs thermal energy from the ambient air while passing through the evaporator plate assembly. The compressor compresses the refrigerant fluid to increase the temperature of the fluid, which is then passed through the heat exchanger so as to transfer thermal energy from the fluid to the water, thereby heating the water. The water is then stored in the tank. The water can be used for any hot water needs, and can be directed through furnace coils so as to dissipate heat to air blown past the coils for heating one or more rooms.
The basic components of the thermal energy recovery system of the present invention are an evaporator plate assembly 10, a compressor 12, a heat exchanger 14, and a hot water storage tank 16. Refrigerant fluid lines 18A, B, C provide a closed circuit loop between the evaporator plate assembly 10, the compressor 12, and the heat exchanger 14. The refrigerant fluid lines 18A, B, C are preferably made of hard copper, or similar material which will withstand rapid pressure increases. Soft copper, such as conventionally used in solar panels, will not suffice. Also, in the preferred embodiment, the fluid line 18A between the evaporator plate assembly 10 and the compressor 12 is ¾ inch diameter, while the line 18B between the compressor 12 and the heat exchanger 14 is ⅜ inch diameter. Thus, the fluid line 18A is low pressure, while the line 18B is high pressure. Water lines 20 provide a circuit between the heat exchanger 14 and the hot water storage tank 16. The size of the compressor 12 in the unit will dictate the sizing of the refrigerant fluid lines 18A, B, C.
A refrigerant accumulator 22 is provided in the fluid line 18A so that any moisture in the refrigerant fluid gas in the line 18A may be precipitated out. A refrigerant receiver 24 is provided in the fluid line 18C between the heat exchanger 14 and the evaporator plate assembly 10 and is used as an expansion chamber or tank. A filter dryer 25 is provided in the fluid line 18C between the heat exchanger 14 and the evaporator plate assembly 10 so as to remove any water in the line. An expansion valve 26 is provided in the line 18C so that the refrigerant fluid changes from a liquid state to a gaseous state as the fluid enters the evaporator plate assembly 10.
A water regulating valve 28 is provided in the water line 20A between the storage tank 16 and the heat exchanger 14. A water pump 30 is provided in the water line 20B between the heat exchanger 14 and the storage tank 16. A thermostat 32 with a submersible temperature probe 34 is provided on the hot water storage tank 16.
A controller 36 is electrically connected to the compressor 12, the water pump 30, and the thermostat 32 so as to control operation of the recovery system, as described below. The controller 36 may be any commercially available, such as model number A4196BF-1C, manufactured by Johnson Control.
The most common use of the thermal energy recovery system of the present invention is with ambient air, particularly outdoor air. In such an application, the evaporator plate assembly 10 is mounted outdoors, with the remaining components being mounted indoors. Thus, with the exception of the evaporator panel assembly 10, the remaining components of the system are housed in an environmentally controlled environment. The evaporator plate assembly 10 may be mounted, for example, on an exterior wall 38 of a building or house. It is understood that the evaporator panel 10 may be located in any environment having ambient thermal energy, whether indoors or outdoors. For example, the evaporator panel assembly 10 may be mounted in waste water, such as from a Laundromat or car wash, to absorb thermal energy from the water; in a hog or cattle confinement building to absorb thermal energy in the air from the body heat of the animals; in a sewage pit to absorb thermal energy from the sludge; and in a Laundromat to absorb thermal energy put out by the dryers. The evaporator plate assembly 10 can also be placed in an indoor swimming pool facilities above the pool to recirculate the thermal energy of the water lost to evaporation of the pool water.
In the method of thermal energy recovery according to the present invention, the refrigerant fluid gas passing through the evaporator panel assembly 10 absorbs thermal energy from the ambient environment. The gas is then compressed by the compressor 12 to increase the temperature of the fluid. As the heated fluid flows through the heat exchanger 14, thermal energy is transferred to water in exchanger 14 to heat the water. The heat exchanger 14 is preferably a coaxial or flat plate unit which allows for efficient transfer of heat from the refrigerant fluid to the water. The heated water is stored in the tank 16.
Operation of the compressor 12 is controlled by the controller 36 in response to the temperature of the water in the storage tank 16. When the temperature in the tank 16 drops below a predetermined point, the thermostat 32 sends a signal to the controller 36 which actuates the compressor 12 so that fluid is pumped through the refrigerant fluid lines 18A, B, C. Simultaneously, the controller 6 actuates the water pump 30 so that water is circulated to and from the heat exchanger 14 through the lines 20A, B. When the temperature of the water in the tank increases to a predetermined level, the thermostat 32 sends a signal to the controller 36, which shuts off the compressor 12 and the water pump 30. The thermostat therefore turns the system on and off predetermined set points. Preferably, the water in tank 16 does not exceed the 120° F., as a safety precaution to preclude burning of a person using the hot water.
A pressure switch 50 is provided in the electrical connection between the compressor 12 and the controller 36 so as to shut off the compressor 12 in the event that there is an excessive pressure build up in the compressor 12. A preferred pressure shut off level is approximately 350 psi.
The water in the tank 16 can be used for numerous needs, such as a shower 40, or for a dishwasher or clothes washer. Also, the hot water can be supplied to coils 42 in a furnace, with a fan or blower 44 blowing air past the coils 42 to heat the air which can then be distributed to one or more rooms. The blower 44 is controlled by a thermostat 46, which also controls a water pump 48 to circulate water between the storage tank 16 and the furnace coils 42.
The evaporator plate assembly 10 functions passively to absorb thermal energy ambient environment. No fan or blower is utilized to force air past the assembly, as in conventional heat pump. Also, since the present system is not used for cooling a room, as is a heat pump, and therefore does not utilize a four-way valve and other more complex pump components. Also, in contrast to a heat pump wherein the compressor and heat exchanger are located outdoors and become nonfunctional below 20° F., the compressor and heat exchanger of the present invention is are located indoors where colder temperatures are not a factor.
The thermal energy recovery method and means of the present invention is a reverse refrigeration technique which absorbs thermal energy from any source at any time, as long as the ambient environment temperature exceeds the boiling point of the refrigerant fluid. A preferred fluid is Freon, which boils at −41° F. Thus, the system will function at temperatures above −40° F., with efficiencies improving as the temperature increases. In an application wherein the plate assembly 10 is absorbing thermal energy from outside air, the system will function 24 hours per day, since there is no need for direct solar rays. Preferably, when the evaporator panel assembly is mounted outdoors, the assembly is located to avoid direct exposure to solar radiation, such as on the north side of a building, so as to prevent sudden pressure increases in the fluid lines, 20A, B, C. Alternatively, a protective cover 52 can be positioned over the assembly 10 to protect the tubing therein from direct exposure to the sun's rays. In other words, the energy from direct sunlight heats the air surrounding the evaporator panel assembly 10, rather than heating the assembly directly, which causes undesirable pressure radiance potential failure of the system. Also, by lowering the working pressure in the system, the compressor can be simplified. For example, the lower pressure eliminates the need for a highly technical variable rotational speed compressor which is difficult to maintain and requires computer technology to operate.
The recovered thermal energy, recovered from the various sources of thermal energy, can also be used as an energy input for different fluids and processes that require the addition of thermal energy to be more efficient. The processes may include heating of soybean oil, heating of ethanol mash, heating of fluids used in radiant floor systems, transfer of thermal energy from one system to a secondary system such as space heating, or adding energy to heat sewage for recovery of greenhouse gasses such as methane.
The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4302942 | Charters et al. | Dec 1981 | A |
| 4314456 | Harnish | Feb 1982 | A |
| 4481788 | Yoshino | Nov 1984 | A |
| 4540874 | Shaffer, Jr. et al. | Sep 1985 | A |
| 4592206 | Yamazaki et al. | Jun 1986 | A |
| 5056588 | Carr | Oct 1991 | A |
| 5255338 | Robinson, Jr. et al. | Oct 1993 | A |
| 5277038 | Carr | Jan 1994 | A |
| 5367602 | Stewart | Nov 1994 | A |
| 5471851 | Zakryk | Dec 1995 | A |
| 5941091 | Broadbent | Aug 1999 | A |
| 6138744 | Coffee | Oct 2000 | A |
| 6212894 | Brown et al. | Apr 2001 | B1 |
| 6408633 | Carr | Jun 2002 | B1 |
