Freon Cascade Refrigerator for Liquid Air Plant Precooler

Abstract

An air liquefier, which employs a Joule-Thomson expansion, consists of the parts illustrated schematically in Figure 1. Leaving the compressor at high pressure and room temperature, air passes through heat exchanger 1 and then enters a refrigerator evaporator where its temperature is reduced. Temperature reduction is accomplished by bringing the air into thermal contact with a refrigerant liquid boiling at reduced pressure. Next, the air passes through another heat exchanger 2 and arrives at the throttling valve V, where it is expanded to atmospheric pressure. Passage through the valve is accompanied by another drop in temperature during the initial or start-up period. The cold air returning through heat exchangers 1 and 2 is made to cool the incoming warm air by thermal contact. In an ideal plant, this warmed gas arrives at the compressor in its original state, the cycle being completed. Sufficient refrigerative effect is produced in the above manner, to lower the air temperature accumulatively at the throttle valve, so that eventually a portion of it will condense after expansion and be withdrawn from the system, Under this circumstance, a fraction x of the incoming air is liquefied while the balance, 1 — x is used to cool the incoming stream.

Reprinted by permission from Refrigerating Engineering, the official publication of the American Society of Refrigerating Engineers, pp. 54-56, April, 1954.