Question

A researcher claims that he has developed an engine, which while working between source and sink temperature of 377°C and 27°C rejects only 50% of absorbed heat. What will be his engine be? (a) An impossible engine (b) A Stirling engine (c) A reversible engine (d) A practical engine

Answer 1

Let the carnot efficiency be n₁ and the engine efficiency be n₂.

n₁ = 1 - T₂/T₁

We write the temperatures in Kelvin.

T₁ = 377 + 273 = 650

T₂ = 27 + 273 = 300

Doing the substitution we have :

1 - (300/650) = 1 - 0.462 = 0.538

= 0.538 × 100 = 53.8%

n₂ = 1 - Q₂/Q₁ = 50%

Since :

n₁ > n₂ the engine is a practical engine.