Patent GB-811713-A (GB)
Title: Improvements in dual capacity refrigeration systems
IPC: F25B9/00
Filed: 1955-06-29
Abstract: 811,713. Refrigerating. GENERAL ELECTRIC CO. June 29, 1955 [June 29, 1954(4)], No. 18836/55. Class 29 A compression system includes two refrigerants which are miscible at condenser temperatures. In one form they are immiscible at evaporator temperatures; in another, they are miscible at higher evaporator temperatures and immiscible at lower evaporator temperatures; in yet another form, they exist in two separate phases of different density and of different refrigerant proportions at evaporator temperatures. As shown in Fig. 1, the dissolved refrigerants flow from receiver 13 to receiver 17 through a pipe 18 under control of a valve 19 actuated by e.g. a float 20 in receiver 17. Some refrigerant flows from receiver 13 to expansion valve 24 and thence to evaporator 25 which cools receiver 17 to cause the formation therein of two refrigerant layers 14, 15 of different volatility. Refrigerant from layers 14, 15 is fed selectively to the main evaporator 22 through a three-way valve 30 actuated by a control 33 in response to the load on the system, to alter the composition of the circulating refrigerant. Refrigerant from the evaporator 25 also flows to evaporator 22 through pipe 26. In a modification, Fig. 3, condenser 12 feeds directly into receiver 17, which is insulated, and from the receiver refrigerant from layers 14, 15 is fed selectively by valve 30 to expansion valve 24, evaporator 25<SP>1</SP> for cooling the receiver and the main evaporator 22. In a modification, Fig. 4 (not shown), condenser 12 feeds refrigerant to the expansion valve whence it flows to the insulated receiver. In this receiver the refrigerants are in solution at higher evaporator temperatures and in two phases at lower evaporator temperatures. Refrigerant flows from the top only of the receiver to the evaporator so that the latter is supplied with the mixed refrigerant or the lighter phase only depending on the evaporator temperature. The system of Fig. 5 is similar to that of Fig. 1, but receiver 17 is cooled by evaporation in part of the refrigerant therein, the receiver being connected to the compressor suction through pipe 38. At higher evaporator temperatures, the refrigerants are in solution in the receiver and, at lower evaporator temperatures they are in two phases 14, 15. Refrigerant, either mixed or phase 14 only depending on evaporator temperature, flows from receiver 17 to evaporator 22 through capillary tube 37. Alternatively, tube 37 may be so connected to the receiver as to supply mixed refrigerant or phase 15 only depending on evaporator temperature. In a modification of the preceding system, Fig. 6 (not shown), the refrigerant flowing from receiver 13 to receiver 17 is precooled by an auxiliary evaporator connected between expansion valve 24 and evaporator 22. In a further modification, Fig. 7, receiver 17 is at condenser pressure and is maintained full of refrigerant from receiver 13 through pipe 18. It is coaled by an evaporator 41 in series with evaporator 22 and contains mixed refrigerant at higher evaporator temperatures and refrigerant in two phases 14, 15 at lower evaporator temperatures. Refrigerant flows from receiver 17 to the high pressure side of expansion valve 24 through capillary tube 37. In a modified system, Fig. 8 (not shown), evaporator 41 is omitted and receiver 17 is cooled by being in the environment of the main evaporator 22. Pairs of refrigerants having suitable characteristics are mentioned in the Specification. The invention is stated to be applicable to systems operating as heat pumps.