In a 15 TR ammonia refrigerator plant the condensing temperature is 250C and the evaporative temperature is -100C. The refrigerant ammonia is subcooled by 50C before passing through the throttle valve. The vapour leaving the evaporator is 0.97 dry. Determine the COP and Power required. The specific heat for liquid is 4.6KJ/Kg0K and for vapour is 2.8KJ/Kg0K.