A two-stage cascade refrigeration system (see Fig. 93) operates between TC = 210 K and TH =

Question:

A two-stage cascade refrigeration system (see Fig. 93) operates between TC = 210 K and TH = 305 K. Intermediate temperatures are T'C = 255 K and T'H = 260 K. Coefficients of performance ω of each stage are 65% of the corresponding value for a Carnot refrigerator. Determine for the real cascade, and compare it with that for a Carnot refrigerator operating between TV and TH.