Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.2 MPa and 200kPa with refrigerant-134a as the working fluid (s. figure B). The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.4 MPa. In the flash chamber, the refrigerant is separated into saturated vapor (point 3) and saturated liquid (point 7). The vapor (point 3) is mixed with the refrigerant leaving the low pressure compressor. The mixture (point 9) is then compressed to the condenser pressure by the high-pressure compressor. The saturated liquid in the flash chamber is throttled to the evaporator pressure and cools the refrigerated space as it vaporizes in the evaporator. The mass flow rate of the refrigerant through the low-pressure compressor is 0.15 kg/s. Assuming the refrigerant leaves the evaporator as a saturated vapor and the isentropic coefficient is 80% for both adiabatic compressors, determine : (a) each point of the refrigeration cycle and show the entire process in a T-s diagram (b) the temperatures of the working fluid at points 2,9, and 4 (c) the mass flow rate of the refrigerant through the high-pressure compressor (d) the rate of heat removal from the refrigerated space in kW (e) the coefficient of performance (COP) of this refrigerator (f) the rate of heat removal and the COP, if this refrigerator operated on a single-stage cycle between the same pressure limits with the same compressor efficiency and the same flow rate as in part (a).