An engineer uses a river (which averages 4°C) to cool his electrical plant, which heats water with a boiler operating at 750°C. What's the maximal performance (in terms of efficiency) theoretically possible for this electrical plant?
A) 64%
B) 36%
C) 27%
D) 73%

Question

Quizplus · Accepted Answer

The maximal theoretical efficiency of a heat engine is given by the Carnot efficiency formula, which is (Th - Tc)/Th, where Th is the absolute temperature of the hot reservoir (in Kelvin) and Tc is the absolute temperature of the cold reservoir (in Kelvin). In this case, Th = 750°C + 273.15 = 1023.15 K and Tc = 4°C + 273.15 = 277.15 K. Therefore, the maximal theoretical efficiency is (1023.15 - 277.15)/1023.15 = 73%. Therefore, the correct answer is D.

An Engineer Uses a River (Which Averages 4°C) to Cool