In one cycle a heat engine absorbs 450 J from a high-temperature reservoir and expels 290 J to a low-temperature reservoir. If the efficiency of this engine is 57% of the efficiency of a Carnot engine, what is the ratio of the low temperature to the high temperature in the Carnot engine?

Answer 1

The actual efficiency is
Wout/Qin = 160/450 = 35.56%
If this is 57% of the carnot efficiency, that latter is 35.56%/.57 = 62.4%

Since the Carnot efficiency is

1 - Tlow/Thigh = 0.624

Tlow/Thigh = 0.376