A two-stage ammonia food-freezing plant with a desired capacity of 528,000 kJ/h at -40°C evaporating temperature and 35°C condensing temperature has a flash intercooling system with a liquid sub cooler.

The vapour leaving the evaporator is at -30°C and entering the first-stage compressor is at -15°C. The vapour leaving the flash chamber is superheated by 10°C in the suction line to the second-stage compressor. Water intercooling is done to cool the vapour to 45°C. Adiabatic efficiencies of both compressors are 0.75. The volumetric efficiencies of first- and second-stage compressors are 0.65 and 0.77 respectively. a) Sketch a fully labelled schematic diagram of the system identifying all the state points and then illustrate the cycle on a (p-h) chart. b) Find the piston displacements, discharge temperatures and power requirements of the two compressors