Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
1999-02-25
2001-09-04
Capossela, Ronald (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
C062S467000, C417S332000
Reexamination Certificate
active
06282908
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to refrigeration or air-conditioning systems which operate over a closed thermodynamic cycle and, more specifically, to refrigeration or air-conditioning systems which utilize the Malone thermodynamic cycle in conjunction with an electromechanical compressor.
2. Description of the Related Art
Most refrigeration and air-conditioning systems currently in operation utilize the Gifford-McMahon thermodynamic cycle wherein phase change (condensation and evaporation) of a recirculating working fluid is utilized as a heat transfer medium. However, temperature restrictions at which the phase change and heat transfer must take place have heretofore limited the choice of working fluids to those classified as either chlorofluorocarbons (CFCs and HCFCs) or hydrofluorocarbons (HFCs). In recent years, severe damage to the environment has been attributed to the release of CFCs and HCFCs into the atmosphere. HFCs, though apparently environmentally safe, have proven to be a relatively expensive alternative. The refrigeration and air- conditioning systems in current use also require mechanical compressors, expanders, and heat exchangers of relatively large volume to handle the phase changes of the working fluid. Thus, allocation of compressor, expander, and heat exchanger space has been a limiting factor in any system design.
The idea to use a medium which is continuously liquid as a working fluid was extensively investigated by John Malone who theorized that an ideal thermodynamic cycle employing an all liquid working fluid (Malone cycle) would have an extremely high efficiency. However, the Malone cycle has not heretofore proven to be commercially viable since in actual practice, its performance has been found to be similar to that obtained using conventional phase change technology. Further investigation of Malone cycle performance demonstrated that nearly half of the total lost inefficiency could be attributed to compressor and expander inefficiency.
The utilization of a working fluid that is continuously in a liquid state (Malone cycle) is known in the art and is exemplified in U.S. Pat. No. 4,353,218 (Wheatley et al.) and U.S. Pat. No. 5,327,745 (Gilmour). It is noted, however, that these patents disclose the employment of mechanical means for providing compression force to the liquid.
U.S. Pat. No. 4,795,318 (Cusack), U.S. Pat. No. 4,842,493 (Nilsson), U.S. Pat. No. 5,215,446 (Takahashi et al.), U.S. Pat. No. 5,525,041 (Deak) and Soviet Union Patents numbers (525,438), (1,222,904), (1,239,420) all disclose electromechanical pumping devices for liquids. Compression of liquid for heat exchange purposes is not contemplated in the instant patents.
U.S. Pat. No. 4,515,534 discloses a electromechanical device for compressing a gas.
None of the above inventions and patents, taken either singularly or in combination, is seen to disclose a refrigeration or air-conditioning system utilizing the Malone cycle thermodynamic system in conjunction with an electromechanical compressor as described and claimed in the instant invention.
SUMMARY OF THE INVENTION
The present invention was conceived as part of an examination of the limitations of current refrigeration/air-conditioning compressor technology. The thrust of the inventive concept is to change the compression task from performing large amounts of work at relatively low frequency to that of performing smaller amounts of work at very high frequency. Reduction of the above concept to practice precluded the use of standard mechanical compressor hardware (pistons, crankshafts, gear pumps, etc.) and suggested the use of piezoceramic or magnetostrictive actuators to perform compression in a thermodynamic environment which would incorporate the Malone cycle in lieu of the Gifford-McMahon cycle.
Piezoceramic or magnetostrictive actuators will elongate and contract with rapid, precisely-controlled strokes of more than 0.1% of their length and with great force when electrically pulsed. These actuator length changes act in a working fluid chamber to cause the working fluid to be alternately compressed, displaced, expanded, and displaced back again according to flow characteristics required in the Malone cycle. Furthermore, piezoceramic actuators are electrically capacitive and can hold an electric charge virtually indefinitely. This characteristic allows piezoceramic actuators to be distended and held against great pressure without continuous current draw, thus reducing the amount of electrical energy input per cycle. The use of piezoceramic or magnetostrictive actuators offers enormous opportunity to achieve high energy efficiency via electronic control of the stroke, wave form, frequency, and coupling resonance of the actuators. An important optimizing feature of the control circuitry, of the present invention, is its ability to seek the resonant frequency of the actuators. It was therefore determined that a piezoceramic or magnetostrictive compressor would enhance the operation of the Malone thermodynamic cycle in performing the refrigeration/air-conditioning function.
The present invention comprises a thermodynamic device that utilizes a non-toxic, environmentally friendly working fluid which is consistently in a liquid phase. A piezoceramic actuator is employed to cause the working fluid to be alternately compressed, displaced, expanded, and displaced back again in accordance with Malone thermodynamic cycle flow. A tubular shell houses the actuator and the working fluid in a sealed chamber. The tubular shell incorporates a novel regenerator assembly which is centered in the working fluid and is coupled to heat-exchange surfaces, which surfaces are mounted to the tubular shell.
Accordingly, it is a principal object of the invention to provide a refrigeration/air-conditioning device operating with a consistently liquid working fluid.
It is another object of the invention to provide a refrigeration/air-conditioning device operating in the Malone cycle thermodynamic mode.
It is a further object of the invention to provide a refrigeration/air-conditioning device which employs a piezoceramic actuator.
Still another object of the invention is to provide a refrigeration/air-conditioning device which utilizes a working fluid that is friendly to the environment.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which are inexpensive, dependable and fully effective in accomplishing their intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
REFERENCES:
patent: 4353218 (1982-10-01), Wheatley et al.
patent: 4501122 (1985-02-01), Cutler
patent: 4515534 (1985-05-01), Lawless et al.
patent: 4795318 (1989-01-01), Cusack
patent: 4842493 (1989-06-01), Nilsson
patent: 5215446 (1993-06-01), Takahashi et al.
patent: 5327745 (1994-07-01), Gilmour
patent: 5525041 (1996-06-01), Deak
patent: 5711157 (1998-01-01), Ohtani et al.
patent: 525483 (1976-11-01), None
patent: 1222904 (1986-04-01), None
patent: 1239420 (1986-06-01), None
Capossela Ronald
Litman Richard C.
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