Provisional Application No. 60/381,374 filed May 17,2002, and U. S. Provisional Application No. 60/384,126 filed May 30, 2002, the entire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION [0002] U. S. Pat. No. 1,781, 541 describes what is now known as the"Einstein Refrigeration Cycle"in which an inert gas (also referred to as a pressure equalizing gas) is introduced into a liquid refrigerant, causing the refrigerant to evaporate due to a lowering of its partial pressure.

Butane was the suggested refrigerant and ammonia was the suggested pressure equalizing gas. In operation, the ammonia is absorbed in cool water in order to separate the ammonia from the butane. The ammonia is then driven out of the water by heating the ammonia-water solution to a temperature of approximately 185 F.

[0003] As recognized by the inventor hereof, a great deal of heat is required to heat the large mass of ammonia-water solution to the required temperature. As a result, the Einstein refrigeration cycle and the ammonia absorption cooling cycle both use more energy than is required by conventional vapor compression refrigeration cycles.

SUMMARY OF THE INVENTION [0004] The inventor hereof has succeeded at designing vapor power cycles which employ selective membranes for separating pressure equalizing gases from vaporized refrigerants. As a result, the vapor power cycles of the present invention can be operated using heat sources having temperatures well below those needed by the Einstein refrigeration cycle and ammonia absorption cooling cycles.

[0005] A refrigeration process according to one aspect of the present invention includes introducing a gas into a liquid refrigerant to vaporize the liquid refrigerant and produce a vapor mixture. The refrigerant absorbs heat in response to vaporizing. The process further includes separating the vapor mixture into the refrigerant and the gas using a selective membrane, with the refrigerant condensing from the gas phase to the liquid phase and rejecting heat in response to the separating.

[0006] An apparatus according to another aspect of the present invention includes an evaporator for evaporating a liquid phase refrigerant containing a gas into a vapor mixture, and a selective membrane for separating the refrigerant and the gas from the vapor mixture.

[0007] A refrigeration apparatus according to another aspect of the present invention includes an evaporator for evaporating a refrigerant from a liquid phase to a gas phase, a condenser for condensing the refrigerant from the liquid phase to the gas phase, and a liquid pump for pumping the refrigerant in liquid phase from the condenser to the evaporator.

[0008] Additional aspects and features of the invention will be in part apparent and in part pointed out below.

BRIEF DESCRIPTION OF THE DRAWINGS [0009] Fig. 1 is a block diagram of a partial pressure refrigeration/heating cycle according to one aspect of the present invention; [0010] Fig. 2 is a block diagram of a vapor power cycle according to another aspect of the present invention; [0011] Fig. 3 is a block diagram of a refrigeration/heating system according to one embodiment of the invention; and [0012] Fig. 4 is a block diagram of a vapor power system according to another embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS [0013] A partial pressure refrigeration/heating cycle according to one aspect of the present invention is illustrated in Fig. 1 and indicated generally by reference character 100. As shown in Fig. 1, the cycle 100 employs an evaporator 102, a selective membrane 104, and a condenser 106. In operation, a pressure equalizing gas 108 is introduced into a liquid refrigerant 110 and the resulting mixture 112 is supplied to the evaporator 102. The refrigerant 110 evaporates in the evaporator 102 in the presence of the pressure equalizing gas 108 due to the fact that the partial pressure of the refrigerant 110 is reduced thereby. A resulting vapor mixture 114 is provided by the evaporator 102 to the selective membrane 104, which physically separates the vapor mixture 114 back into its constituent parts, namely, the pressure equalizing gas 108 and the refrigerant. The separated refrigerant is then provided to the condenser 106, where it condenses back to the liquid phase due to the removal of the pressure equalizing gas 108. The liquid phase refrigerant 110 from the condenser 106 is then mixed again with the partial pressure gas 108 and provided to the evaporator 102, and the cycle continues.

[0014] As indicated by arrow 116 in Fig. 1, the evaporator 102 absorbs heat due to the latent heat of vaporization of the refrigerant 110. Similarly, arrow 118 indicates the heat that is rejected by the condenser 106 due to the latent heat of condensation of the refrigerant. The cycle 100 can thus be used to provide cooling or heating, as appreciated by those skilled in the art. The cycle can also be used to produce useful power, as further described below.

[0015] The selective membrane 104 may be, e. g. , a gas- selective membrane through which the pressure equalizing gas, and not the gaseous refrigerant, can pass or, alternatively, a gas-selective membrane through which the gaseous refrigerant, and not the pressure equalizing gas, can pass.

The selective membrane 104 may also employ multiple selective membranes. The choice of a selective membrane 104 for any given application of the invention will depend upon the type of refrigerant and pressure equalizing gas employed.

[0016] Those skilled in the art will appreciate that, through use of the pressure equalizing gas, the refrigerant can be vaporized in the evaporator at a higher pressure than conventional refrigeration cycles.

[0017] While the cycle of Fig. 1 requires substantially less heat input than the Einstein refrigeration cycle or ammonia absorption cooling, the invention is not so limited, and can be advantageously used with high temperature heat sources as well.

[0018] In one embodiment of the invention, ammonia and butane are utilized as the pressure equalizing gas and the refrigerant, respectively.

[0019] One or more pumps (not shown) may also be included in the cycle 100 of Fig. 1 for circulating the refrigerant and the pressure equalizing gas.

[0020] Fig. 2 illustrates a modified version of the cycle 100 of Fig. 1 in which an energy conversion device 202 is inserted between the evaporator 102 and the selective membrane 104. In this manner, useful power 204 can be produced from the high pressure, high temperature vapor mixture produced within the evaporator. The energy conversion device 202 may be, e. g. , a thermoelectric device for producing electric power from the thermal energy of the vapor mixture, a turbine or power piston for producing mechanical energy by expanding the high temperature, high pressure vapor mixture, etc. Suitable power pistons includes those disclosed in U. S. Provisional Application No.

60/384,788 filed June 3,2002, the entire disclosure of which is incorporated herein by reference.

[0021] In the cycle of Fig. 2, it is assumed that the energy conversion device 202 will sufficiently cool the vapor mixture such that the refrigerant will immediately condense upon being separated from the pressure equalizing gas by the selective membrane 104. Therefore, the condenser 106 and substantial heat rejection 118 of Fig. 1 are not shown in Fig. 2, but can be included in the event that sufficient heat is not removed from the vapor mixture by the energy conversion device 202.

[0022] A preferred system 300 for implementing the cycle 100 of Fig. 1 will now be described with reference to Fig. 3.

As shown therein, the system 300 includes an evaporator 302, a selective membrane 304, a condenser 306, a liquid refrigerant pump 320, a throttle 322, a venturi valve 324, and a heat exchanger 326. In operation, the liquid pump 320 pressurizes the evaporator 302 by pumping liquid refrigerant 310 from the condenser 306 and through the throttle 322 and the venturi valve 324. The passage of the liquid refrigerant 310 through the venturi valve 324 creates suction which draws the pressure equalizing gas 308 through the venturi valve 324 where it becomes entrained in the liquid refrigerant to form a mixture 312. This mixture 312 is provided to the evaporator 302, where it is vaporized and absorbs heat from the external environment to produce heat lift. The resulting vapor mixture is provided to the selective membrane 304, which physically separates the vapor mixture 314 back into the pressure equalizing gas 308 and the refrigerant. Low pressure formed by the venturi valve 324 draws the pressure equalizing gas through the heat exchanger 326, which rejects heat from the pressure equalizing gas to the external environment. The separated refrigerant is provided to the condenser 306, where it condenses back to the liquid phase and rejects heat to the external environment. The liquid phase refrigerant 310 from the condenser 306 is then mixed again with the pressure equalizing gas 308 via the venturi valve 324, and the cycle continues.

[0023] The venturi valve 324 is preferably located within a short distance of the evaporator 302, and may instead be located on or in the evaporator 302. The evaporator 302 may also include a liquid sight glass 328, as shown in Fig. 3.

[0024] Note that in the system 300 of Fig. 3, a refrigeration cycle is provided in which a refrigerant is circulated via the liquid pump 320, which uses only a fraction of the energy required to pump refrigerant in gaseous form (as is commonly done in conventional refrigeration systems).

[0025] Fig. 4 illustrates a modification to the system of Fig. 3 by positioning a turbine 430 between the evaporator 302 and the selective membrane 304. Thus, by expanding the high pressure, high temperature vapor mixture 314 through the turbine 430, useful power can be produced. In one preferred implementation, the (mechanical or electric) power produced by the turbine 430 is used to drive the liquid pump 320. In this manner, the system 400 can be configured as an essentially self-powered (i. e. , the only input is heat) system for producing useful power and/or refrigeration/heating. Suitable turbines include a rotary vane turbine of the type disclosed in U. S. Provisional Application No. 60/360,421 filed March 1,2002, the entire disclosure of which is incorporated herein by reference, a Tesla turbine, and a jet turbine (i. e. , a turbine which utilizes jet propulsion for rotation, and which may or may not be bladeless). Exemplary jet turbines are disclosed in applicant's U. S. Provisional Application No. 60/397,445 filed July 22,2002, U. S. Provisional Application No. 60/400,870 filed August 5,2002, U. S. Provisional Application No.

60/410,441 filed September 16,2002, and U. S. Provisional Application No. [insert no. here] filed December 10,2002 [and entitled"Drum Jet Turbine with Counter-Rotating Ring Method of Manufacture"], the entire disclosures of which are incorporated herein by reference.

[0026] While the condenser 306 is shown in Fig. 4 as rejecting substantial heat to the external environment, this can be omitted if sufficient heat is removed from the vapor mixture 314 by the turbine 430. In fact, it may be possible for the turbine 430 to remove sufficient heat from the vapor mixture 314 as to cause the refrigerant to immediately condense, in which case the liquid refrigerant could be readily separated from the gaseous pressure equalizing gas without requiring use of the selective membrane 304.

[0027] Those skilled in the art will appreciate that many changes can be made in the above embodiments without departing from the spirit and scope of the invention.

Therefore, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.