An air conditioner based on the vapor-compression refrigeration cycle uses R-134a as the working fluid. The air conditioner will used to cool a 0.3 kg/s stream of dry air from 40°C to -5°C. The air conditioner operates in 40°C surroundings and the compressor efficiency is 75%. a) Select evaporator and condenser pressures that will allow heat to be transferred from the air stream to the R-134a in the evaporator, and from the R-134a to the surroundings in the condenser. b) Find the coefficient of performance of the refrigeration cycle. c) Find the power input needed to operate the air conditioner, in kW.

! Required information NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Refrigerant-134a enters the condenser of a residential heat pump at 800 kPa and 50°C at a rate of 0.024 kg/s and leaves at 750 kPa subcooled by 3°C. The refrigerant enters the compressor at 200 kPa superheated by 4°C. (Take the required values from saturated refrigerant-134a tables.) Он 750 kPa (3) Condenser Expansion valve Evaporator +M QL 800 kPa 50°C Compressor Determine the COP of the heat pump. (You must provide an answer before moving to the next part.) The COP of the heat pump 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

Data for steady-state operation of a vapor-compression refrigeration cycle with Refrigerant 134a as theworking fluid are given in the table below. State 1 is at the compressor inlet. The cooling capacity (i.e therate at which heat is removed from the cooled space) is 4.6 tons. 1 ton of refrigeration is equivalent to211 kJ/min. Ignoring heat transfer between the compressor and its surroundings, sketch the ?-? diagramof the cycle and determinea) the mass flow rate of the refrigerant, in kg/min.b) the isentropic compressor efficiency.c) the coefficient of performance.State ? (bar) ? (°C) ℎ (kJ/kg) ? (kJ/kg-K)