Question

What is the Carnot efficiency for a coal–fired power plant?

(a) 65%

(b) 74%

(c) 56%

(d) 90%

I have been asked this question during an online interview.

This interesting question is from I.C Engine topic in division Internal Combustion Engine of Farm Machinery

Answer 1

The correct choice is (c) 56%

To explain: In modern day coal fire power plant, the temperature of high pressure steam (Thot) would be about 400° C and Tcold = 20° C.

η = 1−\(\frac{293}{673}\)

η = 56%.