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.

A vapor-compression refrigeration system which utilizes refrigerant 134a as the working fluid comprises the two-stage compression configuration seen in the schematic below, with intercooling between the stages. 5 Condenser Expansion valve High-pressure compressor 6 3 Flash chamber 9 2 7 Expansion valve Low-pressure compressor Evaporator 1 The direct contact heat exchanger and the flash drum operate at 4 MPa, and the condenser pressure is 1.2 MPa. Saturated vapor at -30 °C enters the first compressor stage. Saturated liquid streams at 0.4 MPa and 1.2 MPa enter the low- and high-pressure expansion valves, respectively. The refrigeration capacity of the system is estimated to be 35.2 kW and each compressor is assumed to operate isentropically. Evaluate each compressor power input and the overall coefficient of performance of the system.

An ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid is maintains a condenser at 1000 Kpa and the evaporator 40C. Determine the COP and the amount of power required to service a 400 KW cooling load.

3) A cascade refrigeration system uses R22 in the low temp unit and R12 in the high temp unit. The system develops 28 kW of refrigeration at -45°C. The R12 system operates at -12°C evaporating temp and 40°C condensing temp. There is a 10° overlap of temperatures in the cascade condenser. Calculate the power required by R22 compressor, and the power required R12 compressor.

The ordinary household refrigerator is a good example of the application of this cycle. Evaporator Freezer compartment Capillary ube Kitchen air 25°C -18°C Condenser coils 3°C Comprosor HW: Q1: Refrigerant-134a is the working fluid in an ideal compression refrigeration cycle. The refrigerant leaves the evaporator -20°C and has a condenser pressure of 0.9 MPa. The mass flow rate is 3 kg/min. Find COP,, COPR. Camat for same Tmas and Tmin, and the tons of refrigeration. Q2: A simple VCRC using R-134a operates with a condensing temperature of 30°c and an evaporating temperature of -20°c .The system produces 50 kw of refrigeration. Determine the : a) Thermodynamic property values at the four main state points of the cycle, b) COP, c) Rate of refrigerant flow. Another measure of the effectiveness of the refrigeration cycle is how much input power to the compressor, in horsepower, is required for each Ton of cooling. The unit conversion is 4.715 hp per Ton of cooling To convert from COP to…

4. A refrigerating plant having R-12 as the working fluid, comprises three evaporators of 10 TR at -10°C, 20 TR at 5°C and 30 TR at 10°C. Each of the evaporators is having the individual expansion valve arrangement. The refrigerant from the higher stage expansion valve is bled and mixed with delivery from the lower stage compressor and sent to the higher stage compressor suction thus effecting intercooling of the delivery gas from the lower stage and bringing the suction of the higher stage compressor to dry and saturated conditions. There is only one condenser operating at 40°C and sub- cooling the liquid refrigerant to 30°C. The compression during each stage of compression may be assumed isentropic. The evaporator discharge is dry saturated in cach of the evaporators. Determine the power required by the entire system. 5. A refrigeration system using R-12 as refrigerant consists of three evaporators of capacities 20 TR at - 5°C, 30 TR at 0°C and 10 TR at 5°C. The vapours leaving the…

Subject Thermodynamics. Instructions: Don't round off in the process. Just round off in the final answer with 2 decimals only. Use 273.15 K to convert Celsius to Kelvin

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)