In the case of a refrigeration system undergoing an irreversible cycle, $$\oint {{{SQ} \over T}} $$ is _____________$$\left( { < 0/ = 0/ > 0} \right)$$

Any thermodynamic cycle operating between two temperature limits is reversible if the product of efficiency when operating as a heat engine and the coefficient of performance when operating as a refrigeration is equal to $$1.$$

A reversible heat transfer demands:

A condenser of a refrigeration system rejects heat at a rate of $$120$$ $$kW,$$ while its compressor consumes a power of $$30$$ $$kW.$$ The coefficient of performance of the system would be