METHOD OF REFRIGERATION WHICH COMBINES TWO THERMODYNAMIC CYCLES AND A CRYOGENIC MACHINE FOR CARRYING OUT SAID METHOD

摘要

1456420 Refrigerating COMMISSARIAT A L'ENERGIE ATOMIQUE 26 June 1974 [6 July 1973] 28385/74 Heading F4H A refrigeration system uses two distinct gas circulation systems in which the gases are subjected to two different thermo-dynamic cycles, each consisting of compression, cooling, expansion and reheating, the two systems being coupled so that at least one operation of each cycle initiates an operation of the other. In the apparatus described one cycle 140 is a Claude cycle using a uni-directional circulation of gas from a compressor and cooler 136 to the space C1 in which it is expanded by downward movement of piston 130. The other cycle 142 is a Stirling cycle and uses a reciprocating gas flow between spaces CSP1/SP and C2, the piston 130 acting as a displacer causing the gas to flow through ducts 132 which contain heat accumulators 134. The piston is returned to its uppermost position by movement of a piston 128, compressing the gas in space C2. In operation the valve 124 opens when the piston 130 is at its top position to admit cold gas under high pressure. This pushes down the piston, the gas expanding and getting colder. The downward movement of the piston transfers gas from space C2 to spaces CSP1/SP. The piston 130 is moved further downwards as piston 128 descends. Exhaust valve 126 then opens to allow the cold gas in space C1 to be expelled as the piston 130 rises again under the influence of rising piston 128. Cold may be extracted from the upper Claude system only or from the lower Stirling system only or from both. The purpose of combining the two systems is to balance the conditions of temperature and pressure in spaces C1 and CSP1/SP so that difficulties of sealing and insulation are avoided. External ducts and heat accumulators may replace those within piston 130. The pressure of the gas in the lower space C2 can be varied by other means, e.g. by alternate connection to high and low pressure sources 150, 152. The Stirling machine may be replaced by a Taconis or Vuilleumier type or a pulse tube machine.