The least rate of heat rejection per kW net output of engine is

Question

In a cyclic heat engine operating between a source temperature of 600⁰C and sink temperature of 20⁰C, the least rate of heat rejection per kW net output of engine is                      

(a) 0.588 kW                    (b) 0.650 kW

(c) 0.505 kW                    (d) 0.460 kW