Question

what is the highest cycle efficiency possible for heat engine operating between 800 and 15

Answer 1

Maximum efficiency is for engines.

For engines, we have

$T1​=15+273=288K$

$T2​=800+273=1073K$

$η=\frac{T2​−T1}{T2}​$

​$η=\frac{1073​−288}{1073}​ =0.7315$

$η =0.7315$

Hence, 73.15%.