A solar collector receiving solar radiation at the rate of $$0.6$$$$kW/{m^2}$$ transforms it to the internal energy of a fluid at an overall efficiency of $$50\% $$. The fluid heated to $$350$$ $$K$$ is used to run a heat engine which rejects heat at $$313$$ $$K.$$ If the heat engine is to deliver $$2.5$$ $$kW$$ power, then minimum area of the solar collector required would be

A heat engine having an efficiency of $$70\% $$ is used to drive a refrigerator having a coefficient of performance of $$5.$$ The energy absorbed from low temperature reservoir by the refrigerator for each $$kJ$$ of energy absorbed from high temperature source by the engine is

A Carnot cycle is having an efficiency of $$0.75.$$ If the temperature of the high temperature reservoir is $${727^ \circ }C,$$ what is the temperature of low temperature reservoir?

A cyclic heat engine does $$50$$ $$kJ$$ of work per cycle. If the efficiency of the heat engine is $$75\% $$, then heat rejected per cycle is