A system undergoes a refrigeration cycle, receiving Qc by heat transfer at a temperature Tc and discharging energy Oh by heat transfer at a higher temperature Th. There are no other heat transfers. (a) Using energy and exergy balances, show that the net work input to this cycle cannot be zero. (b) Show that the cycle performance coefficient can be expressed by Tc (7.-T.) (1 Ea T.QH-Qc) where Ed is the exergy destruction and To is the temperature of the reference environment for exergy. (c) Using the result of part (b), obtain an expression for the theoretical maximum value of the coefficient of performance