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.

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.

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter45: Domestic Refrigerators And Freezers

Section: Chapter Questions

Problem 9RQ: The defrost cycle in a domestic refrigerator may be terminated by two methods: ___and___.

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J 5 A Carnot refrigeration cycle is used to maintain a room at 23 °C by removing heat from groundwater at 15 °C. Refrigerant R-134a enters the condenser as saturated vapor at 40 °C and leaves as saturated liquid at the same temperature. The evaporator pressure is 351 kPa. a) If the room is to receive 2kW, what is power input to the compressor? b) Net power input to cycle?
R134a refrigeration system operates in an ideal vapor-compression refrigeration cycle. The temperature of the condenser and evaporator are 46 C and -2 C respectively. The cooling effect of the refrigerator is 15 kW. Calculate a) mass flow rate of the refrigerant b) work input to the compressor c) heat rejection in the condenser d) what is the maximum COP if this refrigerator operates in Carnot refrigeration cycle?
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)
R-134a is used as the working fluid in the ideal two-stage vapor compression refrigeration system. Working pressures for evaporator, evaporation chamber and mixing chamber, condenser are given as 1, 4 and 9 bar, respectively. If the cooling load is 5 tons a) the compressor power on the low pressure side (kW) b) the mass flow rate of the fluid entering the mixing chamber (kg/min) c) find the COP of the entire cycle.
A steady-flow Carnot refrigeration cycle uses refrigerant-134a as the working fluid. The refrigerant changes fromsaturated vapor to saturated liquid at 60C in the condenser asit rejects heat. The evaporator pressure is 140 kPa. Show thecycle on a T-s diagram relative to saturation lines, and determine(a) the coefficient of performance, (b) the amount ofheat absorbed from the refrigerated space, and (c) the net workinput.
An R-134a vapor compression cycle, has a refrigeration load of 3 tones. The evaporator and condenser temperatures are -20°C and 40°C respectively. Determine (a) the refrigerant flow rate in kg/s, (b) the volume flow rate handled by the compressor in m3/s, (c) work input to the compressor in kW, (d) heat rejected in the condenser in kW (e) the isotropic discharge temperature. If there is a 5°C of superheating of vapor before it enters the compressor, and 5°C sub cooling of liquid before it flows through the expansion valve, determine the above quantities. (Cp liquid and Cp vapor values are 0.963 and 0.6165 kJ/kg K respectively).
A window air conditioner uses R22, the evaporator pressure is 0.5 MPa and the condenser pressure is 2.15 MPa. The cooling capacity is 2 TR. The temperature of the refrigerant exits the compressor is 85C. The refrigerant is saturated vapor at the inlet of the compressor and no subcooling. Determine the mass flowrate of the cycle.
R134a refrigeration system operates in an ideal vapor-compression refrigeration cycle. The temperature of the condenser and evaporator are 46 C and -2 C respectively. The cooling effect of the refrigerator is 15 kW. Calculate a) mass flow rate of the refrigerant b) work input to the compressor c) heat rejection in the condenser d) what is the maximum COP if this refrigerator operates in Carnot refrigeration cycle? * [ a)04s7kgrs 01136 ky/s )0739kg/s O a)0327kars b) 2.45kW O vasrkw b)134ky/s b)3.306 kw O o2342kw ) 18.294 kW 1161 kW O g97kw d)556 O d400 43712 d4)6.872
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. A refrigerator uses refrigerant-134a as the working fluid and operates on the vapor-compression refrigeration cycle. The evaporator and condenser pressures are 100 kPa and 1400 kPa, respectively. The isentropic efficiency of the compressor is 88 percent. The refrigerant enters the compressor at a rate of 0.022 kg/s superheated by 26.37°C and leaves the condenser subcooled by 4.4°C. Problem 11.021.a - Actual refrigeration cycle Determine the rate of heat removal from the refrigerated space, the rate of heat rejection from the refrigerant to the environment, the power input, and the COP. (Take the required values from saturated refrigerant-134a tables.) The rate of heat removal from the refrigerated space is kW. The rate of heat rejection from the refrigerant to the environment is kW. The power input is kW. The COP is .
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. A refrigerator uses refrigerant-134a as the working fluid and operates on the vapor-compression refrigeration cycle. The evaporator and condenser pressures are 100 kPa and 1400 kPa, respectively. The isentropic efficiency of the compressor is 88 percent. The refrigerant enters the compressor at a rate of 0.022 kg/s superheated by 26.37°C and leaves the condenser subcooled by 4.4°C. Problem 11.021.b - Comparison to ideal vapor compression cycle Determine the rate of heat removal from the refrigerated space, the rate of heat rejection from the refrigerant to the environment, the power input, and the COP if the cycle is operated on the ideal vapor-compression refrigeration cycle between the same pressure limits. (Take the required values from saturated refrigerant-134a tables.) The rate of heat removal from the refrigerated space is kW. The rate of heat rejection from…
A Carnot vapor refrigeration cycle uses R-134a as the working fluid. The refrigerarit enters the condenser as saturated vapor at 28°C and leaves as saturated liquid. The evaporator operates at a temperature of -10°C. For every kg of refrigerant flow, calculate the work of compression, kJ
QUESTION 2 The reason for the reversed carnot cycle not to be suitable for refrigeration cycles is a. Not effecient b. The COP dcreases as the Condenser temperature rises and the evaporator temperature falls c. The isentropic processes are not practical d. It requires an oversized compressor