Question

300 kJ/s of heat is supplied at a constant fixed temperature of 290°C to a heat engine. The heat rejection takes place at 8.5°C. The following results were obtained : 

(i) 215 kJ/s are rejected. 

(ii) 150 kJ/s are rejected. 

(iii) 75 kJ/s are rejected. 

Classify which of the result report a reversible cycle or irreversible cycle or impossible results.

Answer 1

Heat supplied at 290°C = 300 kJ/s 

Heat rejected at 8.5°C : (i) 215 kJ/s, (ii) 150 kJ/s, (iii) 75 kJ/s. 

Applying Clausius inequality to the cycle or process, we have :

= 0.5328 – 0.2664 = 0.2664 > 0. 

This cycle is impossible by second law of thermodynamics, i.e., Clausius inequality.