At what lower temperature does a reversible engine operating from a high temperature of 600 K have the same efficiency as another reversible engine operating between 400 K and 750 K?

Question

Quizplus · Accepted Answer

The efficiency of a reversible engine is given by 1 - (T_cold/T_hot). For the first engine, efficiency is 1 - (T_cold/600). For the second engine, efficiency is 1 - (400/750). Setting these equal gives T_cold = 320 K.

At What Lower Temperature Does a Reversible Engine Operating from a High