Cryogenic Refrigeration Method And Device

Abstract

The invention relates to a cryogenic refrigeration device intended to transfer heat from a cold source to a hot source via a working fluid flowing through a closed working circuit including the following portions in series, namely: a portion for the substantially isothermal compression of the fluid, a portion for the substantially isobaric cooling of the fluid, a portion for the substantially isothermal expansion of the fluid, and a portion for the substantially isobaric heating of the fluid. The compression portion of the working circuit includes at least two compressors disposed in series and the expansion portion of the working circuit includes at least one expansion turbine, said compressors and expansion turbine(s) being driven by at least one high-speed motor including an output shaft. One end of the output shaft supports and rotates, by means of direct coupling, a first compressor, while the other end of the output shaft supports and rotates, by means of direct coupling, a second compressor or an expansion turbine.

1 - 10 . (canceled) 
     
     
         11 : A cryogenic refrigeration device for transferring heat from a cold source to a hot source via a working fluid flowing through a closed working circuit, the working circuit comprising in series;
 a) a portion for the substantially isothermal compression of the fluid,   b) a portion for the substantially isobaric cooling of the fluid,   c) a portion for the substantially isothermal expansion of the fluid, and   d) a portion for the substantially isobaric heating of the fluid,   the compression portion of the working circuit comprising;   e) at least two compressors disposed in series and   f) at least one heat exchanger for cooling the compressed fluid disposed at the outlet of each compressor,   the expansion portion of the working circuit comprising;   g) at least one expansion turbine and   h) at least one heat exchanger for heating the expanded fluid,   wherein the compressors and the expansion turbine(s) are driven by at least one high-speed comprising;   i) an output shaft whereof one end supports and rotates, by means of direct coupling,   j) a first compressor and whereof the other end supports and rotates, by means of direct coupling,   k) a second compressor or an expansion turbine, and in that   l) the compressors are of the centrifugal compression type, and in that   m) the expansion turbine(s) are of the centripetal expansion type, and in that   n) the output shafts of the motors are mounted on magnetic or dynamic gas bearings, said bearings being used to support the compressors and the turbine sand in that   o) the cooling portion and the heating portion comprise a common heat exchanger through which the working fluid flows in countercurrent according to whether it is cooled or heated.   
     
     
         12 : The device of  claim 11 , wherein the working circuit comprises a volume forming a buffer storage chamber for the working fluid. 
     
     
         13 : The device of  claim 11 , wherein the working fluid is in the gas phase and is composed of a pure gas or a mixture of pure gases selected from the group consisting of: helium, neon, nitrogen, oxygen, argon, carbon monoxide, methane, or any other fluid having a gas phase at the temperature of the cold source. 
     
     
         14 : The device of  claim 11 , wherein the number of compression stages is higher than the number of expansion stages. 
     
     
         15 : The device of any  claim 11 , further comprising at least one motor whereof at least one end of the output shaft rotates, by means of direct coupling, at least two wheels. 
     
     
         16 : The device of  claim 15 , further comprising at least one motor whereof one end of its output shaft rotates, by means of direct coupling, two compressor impellers, the other end of the output shaft rotating, by means of direct coupling, a turbine wheel. 
     
     
         17 : A cryogenic refrigeration method for transferring heat from a cold source to a hot source via a working fluid flowing through a closed working circuit, the working circuit comprising in series;
 a) providing a compression portion comprising at least two compressors disposed in series,   b) providing a fluid cooling portion,   c) providing an expansion portion comprising at least one expansion turbine, and   d) providing a heating portion,   the method comprising a working cycle comprising;   e) compressing, substantially isothermally, the fluid in the compression portion by cooling the compressed fluid at the outlet of the compressors,   f) cooling, substantially isobaricly, the fluid in the cooling portion,   g) expanding, substantially isothermally, the fluid in the expansion portion by heating the expanded fluid at the turbine outlet, and   h) heating, substantially isobaricly, the fluid having exchanged heat with the cold source),   the fluid working cycle (temperature T, entropy S) being of the reverse Ericsson type,   i) cooling, during the first substantially isothermal compression step, the compressed fluid at the outlet of each compressor to keep the fluid temperatures at the inlet and outlet of each compressor substantially equal and preferably within a range of about 10 K,   j) cooling, during the third substantially isothermal expansion step, the expanded fluid at the outlet of each turbine to keep the fluid temperatures at the inlet and outlet of each turbine substantially equal and preferably within a range of about 5 K,   k) driving the compressors and the expansion turbine(s) by at least one high-speed motor comprising an output shaft whereof one end supports and rotates, by means of direct coupling, a first compressor and whereof the other end supports and rotates, by means of direct coupling, a second compressor or an expansion turbine, and in that   l) transferring part of the mechanical work of the turbine(s) to the compressor(s) via the output shaft(s), and in that   m) mounting the output shafts of the motors on magnetic or dynamic gas bearings, said bearings being used to support the compressors and turbines, and in that the cooling portion and the heating portion comprise a common heat exchanger through which the working fluid flows in countercurrent according to whether it is cooled or heated.   
     
     
         18 : The method of  claim 17 , wherein on completion of the second cooling step, the working fluid is cooled to a low temperature of about 60 K and in that the working circuit comprises a number of compressors that is three times higher than the number of expansion turbines. 
     
     
         19 : The method of  claim 17 , wherein the working fluid is used to cool or to keep cold superconductor elements at a temperature of about 65 K. 
     
     
         20 : The method of  claim 17  wherein the temperature drop of the fluid constituting the cold source is substantially identical to the temperature rise of the working gas in heat exchanger