Q31 An ideal vapor-compression refrigeration cycle works on R-12 and operates between (42 °C and -5C saturation conditions). the exit of the compressor (h₂) is at superheated conditions at 390 kPa and entropy S = 1.562 kJ/kg.K. 1- Draw the cycle on T-S diagram. 2- Calculate the refrigeration effect. 3- The heat removed to the environment. h2 S2 P2 12 P2= R3 51=32 17 marks) 4- The work supplied to the compressor. 52 = 5.1. R

Q31 An ideal vapor-compression refrigeration cycle works on R-12 and operates between (42 °C and -5C saturation conditions). the exit of the compressor (h₂) is at superheated conditions at 390 kPa and entropy S = 1.562 kJ/kg.K. 1- Draw the cycle on T-S diagram. 2- Calculate the refrigeration effect. 3- The heat removed to the environment. h2 S2 P2 12 P2= R3 51=32 17 marks) 4- The work supplied to the compressor. 52 = 5.1. R

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

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

See similar textbooks

Similar questions

The defrost cycle in a domestic refrigerator may be terminated by two methods: ___and___.
Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 270 K. The compressor pressure ratio is 3 and the temperature at the turbine inlet is 310 K. Determine:d).the coefficient of performance of a Carnot refrigeration cycle operating between thermal reservoirs at TC 270 K and TH 310 K, respectively. The above Brayton refrigeration cycle is modified by introducing a regenerative heat exchanger. In the modified cycle, the compressed air enters the regenerative heat exchanger at 310 K and is cooled to 280 K before entering the turbine. Determine for the modified cycle:(e).the lowest temperature, in K.f).the net work input per unit mass of air flow, in kJ / kg.
Consider the ideal vapor compression cycle operating between 1.4 bar and 9bar using R-125 as the refrigerant, which removes heat from a cold space at a rate of 100kW. If the evaporator outlet was suddenly superheated by 2℃ above saturation, what will be the resulting effect on the cycle? a.Refrigerant flowrate will decrease, Condenser duty will decrease b.Refrigerant flowrate will increase, Condenser duty will decrease c.Refrigerant flowrate will increase, Condenser duty will increase d.Refrigerant flowrate will decrease, Condenser duty will increase
14 - The evaporator of a refrigeration machine operating with an ideal vapor compression cycle using refrigerant – 134a (refrigerant, R–134a) is kept at 4ºC. The enthalpy value at the compressor output is required to be 280 kJ/kg. If the cooling load is 170 kJ/kg, which of the following is the value of the coefficient of performance? a) 6.43 B) 6.58 NS) 3.07 D) 3.39 TO) 6.24
A standard vapor compression system produces 70.4 kW of refrigeration using R-12as a refrigerant while operating between a condenser temperature of 42 °C and anevaporator temperature of –25 °C.2.1 Draw the p-h diagram of the cycle. 2.2 Determine:(a) the refrigerating effect in kJ/kg, (b) the circulating rate in kg/s, (c) the power supplied, (d) the COP, (e) the heat rejected in kW, and(f) the volume flow rate in m3/s.
A 105 x 205 mm reciprocating R134a compressor operates with a suction pressure of 0.2928 MPa and a condenserpressure of 1.2 MPa. The cycle frequency is 23 cps. The evaporator load is 12.8 tons. The mechanical efficiency ofcompressor is 75%. The clearance volume of compressor is 5% (a) Draw the ph Diagram and Refrigeration System Diagram(b) enthalpy and temperature of superheated vapor (show interpolation)(c) mass of flash vapor entering evaporator, kg vapor/kg refrigerant(d) mass of refrigerant recirculated, kg/s(e) condenser load, kW(f) volume capacity of isentropic compressor at suction, L/s(g) volume displacement of compressor, L/s(h) actual volumetric efficiency, %(i) clearance volumetric efficiency(j) power requirement of isentropic compressor, kW(k) coefficient of performance(l) brake power output of electric motor, kW to drive isentropic compressor(m) power requirement of polytropic compressor, kW for compression efficiency of 80%
A standard ammonia vaporcompression cycle developing 20 tons of refrigeration operates with a condensing temperature of 32°C and an evaporating temperature of 14°C. Calculate the (a) refrigerating effect, (b) circulating rate of refrigerant, (c) theoretical power, (d) COP, (e) gallons per minute of cooling water in the condenser, if ∆t is 8°C, (f) quality of the refrigerant entering the evaporator, and (g) temperature of the refrigerant leaving the compressor. (1 gallon contains 8.33 lb. of water) Answers: (a) 1093.7 kJ/kg, (b) 3.86 kg/min., (c) 15.44 kW, (d) 4.56, (e) 40.6 gpmShow your complete solution.
Consider the ideal vapor compression cycle operating between 1.2 bar and 8 bar using R-410A as the refrigerant, which removes heat from a cold space at a rate of 100kW. If the condenser outlet was subcooled by 2°C below saturation, which of the following is TRUE?I. The required mass flow of the refrigerant will decrease.II. The COP of the ref will increase. a. Neither I nor IIb. I onlyc. II onlyd. Both I and II
A refrigerator operates on an ideal vapour-compression refrigeration cycle and uses refrigerant R−134?? as the working fluid. The condenser operates at 1.6MPa and the evaporator at −6℃. If an adiabatic, reversible expansion device were available and used to expand the liquid leaving the condenser, how much would the COP improve by using this device instead of the throttle device?
A refrigerator operating using vapor-compression cycle uses R-134a as a working fluid. The condenser temperature is 65oC and the evaporator temperature is -15oC. The compressor operates at 80% efficiency. a. Determine the coefficient of performance of the refrigeration cycle. b. How much refrigerant is needed to deliver 3 kW of cooling? c. Sketch the vapor compression cycle indicating the states of each stream (in terms of H, P, T, and S) and showing the values of energy input/output in the system d. Suppose that we replace the expansion valve in the vapor- compression cycle with a turbine that operates at 80% efficiency. Determine the coefficient of performance of the refrigeration cycle. Provide the new state properties (i.e. H, P, T and S) for this changes Please use CATT for any values needed
A8 A controlled-temperature storage room is maintained at the desired temperature by an R-134a refrigeration unit with evaporator and condenser temperatures of –20oC and 40oC respectively. Sketch a fully labelled-diagram of the cycle on pressure-enthalpy co-ordinates. Use the combination of tables and the superheated region for refrigerant R-134a to answer this question.
Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 270 K. The compressor pressure ratio is 3 and the temperature at the turbine inlet is 310 K. Determine:The above Brayton refrigeration cycle is modified by introducing a regenerative heat exchanger. In the modified cycle, the compressed air enters the regenerative heat exchanger at 310 K and is cooled to 280 K before entering the turbine. Determine for the modified cycle:f).the net work input per unit mass of air flow, in kJ / kg. g).the cooling capacity, per unit mass of air flow, in kJ / kg.h).the coefficient of performance.