Question

if a 35% efficient carnot engine is run in reverse to form a refrigerator, what is its COP(COEFFICIENT OF PERFORMANCE)?

Answer 1

The efficiency of carnot engine is e = 35% = 0.35

The coefficient of performance is COP = Q_L/(Q_H - Q_L)

The efficiency of carnot engine is e = W/Q_H

Thus, the relation between efficiency and COP is,

  e = 1 / (k + 1)

                      k+1 = 1/e

                         k = (1/e)-1

                            = (1/0.35) - 1

                            = 1.85