An air conditioner using refrigerant-134a as the working fluid and operating on the ideal vapor-compression refrigeration cycle is to maintain a space at 36.00°C while operating its condenser at 1600 kPa. Determine the COP of the system when a temperature difference of 4.000°C is allowed for the transfer of heat in the evaporator. (Take the required values from saturated refrigerant-134a tables.) (Round the final answer to three decimal places.) The COP of the system is

Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.4 MPa and 280 kPa using refrigerant-134a as the working fluid. The heat rejection from the lower cycle to the upper cycle occurs in an adiabatic counterflow heat exchanger where the pressures in the upper and lower cycles are 0.5 MPa and 600 kPa, respectively. In both cycles, the refrigerant exits the condenser as a saturated liquid and enters the compressor as a saturated vapor. The isentropic efficiency of the compressors is 85 percent. Given the mass flow rate of the refrigerant through the lower cycle is 0.18 kg/s, calculate: (a) The mass flow rate of the refrigerant through the upper cycle. (b) The rate of heat extraction from the cooling area. (c) The Coefficient of Performance (COP) of this refrigeration system.

An air conditioner using refrigerant-134a as the working fluid and operating on the ideal vapor-compression refrigeration cycle is to maintain a space at 22°C while operating its condenser at 1000 kPa. Determine the COP of the system when a temperature difference of 2°C is allowed for the transfer of heat in the evaporator. (Take the required values from saturated refrigerant-134a tables.) The COP of the system is

The figure below shows a two-stage vapor-compression refrigeration system with ammonia as the working fluid. The system uses a direct-contact heat exchanger to achieve intercooling. The evaporator has a refrigerating capacity of 40 tons and produces -30°F saturated vapor at its exit. In the first compressor stage, the refrigerant is compressed adiabatically to 140 lbf/in.², which is the pressure in the direct contact heat exchanger. Saturated vapor at 140 lbf/in.² enters the second compressor stage and is compressed adiabatically to 250 lbf/in.² Each compressor stage has an isentropic efficiency of 85%. There are no significant pressure drops as the refrigerant passes through the heat exchangers. Saturated liquid enters each expansion valve. Determine: Expansion valve 6- Condenser Direct contact heat exchanger Expansion valve (a) the ratio of mass flow rates, m3/my. (b) the power input to each compressor stage, in horsepower. (c) the coefficient of performance Comp Comp Evaporator