In an aircraft refrigeration unit air is bled from the engine compressor at 3.5 bar and 2700 C and is passed through an air cooled heat exchanger. The refrigerant air bleed leaves the exchanger at 3.5 bar and 750 C and is expanded through a turbine to 0.76 bar. The isentropic efficiency of the turbine is 85%. The air is then delivered to the aircraft cabin and leaves the aircraft at 160 C. Calculate
i. The refrigerating effect
ii. The power developed by the air turbine per unit mass flow rate.