Question

A Carnot engine operating between 900℉ and 90℉ produces 40,000 ft.lb of work. Determine (a) the heat supplied, (b) the change of entropy during heat rejection, (c) the thermal efficiency of the engine.

Answer 1

a)

$Q_2=Q_1\frac{T_2}{T_1}=99000~ft.lb,$

b)

$S=\frac{Q_2}{\Delta T}=298~\frac JK,$

c)

$\eta=1- \frac{T_2}{T_1}=0.5=50\%.$