Patent GB-526616-A (GB)
Title: Improvements in absorption refrigerating systems of the inert gas type
IPC: F25B15/10
Filed: 1939-03-22
Abstract: 526,616. Refrigerating. ELECTROLUX, Ltd. March 22, 1939, No. 9104. Convention date, March 24, 1938. [Class 29] Absorption systems. - In a continuous-cycle inert gas system in which gas circulation is effected by differences in densities of gas columns, the flow of the inert gas in a part of the evaporator is varied in response to the load on the evaporator, so that for example when a fresh tray of water to be frozen is inserted in a part of the evaporator, rapid cooling effect is produced in that part. The variation is effected by accumulating a pool of liquefied refrigerant at the bottom of the evaporator to seal a byepass conduit for the gas mixture, and unsealing this byepass under load conditions until the pool is evaporated, after which it again reforms. The refrigerating system comprises the usual generator 10, condenser 11, evaporator 12, absorber 14, gas heat exchanger 24 and a gas vessel 36 connected to the condenser and to the rich gas conduit 23 of the gas heat exchanger. The evaporator comprises an upper cabinetcooling part 12a and lower ice-making, parts 12b, 12c, and the pool 49 is formed at the bottom of the lowest part. A thermal element 45 in contact with the lowest part controls a valve 47 in the fuel supply to the generator. The evaporator conduits consist of coils 38a ... 38f which are U-shaped and closed at their forward ends and connected at their rear ends by bends 39 and by a vertical conduit 39<1>. The uppermost part is finned, whereas the lower parts are separately enclosed in shells 42 adapted 'to receive ice trays 44, the lowest serving as a quick-freezing part. A conduit 52 extends from the pool chamber 49 upwards to the closed end of the top coil 38a. Liquid refrigerant flows from the condenser through a conduit 18 to the top coil 38a and downwards through the coils 38b, 38c to coil 38d and weak inert gas flows from the gas heat exchanger through a conduit 21 to the coil 38e, and thence through coil 38f, pipe 39<1> to coils 38d and further upward. A dam 53 is formed in the coil 38d and accumulated liquid flows therefrom through a seal 54 to the coil 38e at a point where the weak gas enters. Thus in coils 38c and 38f the refrigerant is in parallel flow with inert gas and in the other coils is in counterflow. With moderate load liquid refrigerant accumulates in the pool 49 and seals conduit 52. On an increase of load due for example to warm atmosphere the pool tends to diminish and the conduit 52 is open to flow of relatively weak gas to the top coil The partial pressure of refrigerant in the upper coils will increase, however, because of the diminished flow of inert gas thereto, and less refrigerant will evaporate therein and the pool will reform with refrigerant pre-cooled in the upper coils. The weak inert gas is also cooled in the coils 38c, 38f so that when, even under load conditions, a fresh tray of water is inserted in the lowest section, rapid freezing occurs and the conduit 52 again opens to byepass the inert gas from the intermediate sections, where the cooling effect is slowed down. As soon as the water is frozen the pool re-forms and normal circulation takes place.