EFFECT OF DISCHARGE PRESSURE

The discharge (or condenser) pressure p_d increases to p_d’ due to frictional resistance to flow or refrigerant. The effects of increase in discharge pressure are (Fig. 19.17):

1. The refrigerating effect decreases from (h₁ − h₄) to (h₁ − h_4’).
2. The compression work increases from (h₂ − h₁) to (h₂ − h1).

Figure 19.17 p-h diagram

Thus the COP decreases. The effect of increase in discharge pressure is similar to that of decrease in suction pressure.