A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.29 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of 430 W from the surroundings. The heat exchanger loses no heat to the environment.

A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.29 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of 430 W from the surroundings. The heat exchanger loses no heat to the environment.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

A heat pump uses R134a as refrigerant. The refrigerant flows into the condenser at 900 kPa and 60°C and flows out of it (the condenser)as saturated liquid at the same pressure. The pressure in the evaporator is 70 kPa. The mass flow of the refrigerant is 0.025 kg/s and the compressor power is 1.4 kWa) Calculate the heat pump's power factor, COPHP.b) Calculate how much heat is absorbed/taken up from the air outside.c) Calculate the vapor quality of the refrigerant into the evaporator.
Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and -10oC at rate of 0.05 kg/sec and leave at 0.8 MPa and 50oC. The refrigerant is cooled in the condenser to 26oC and 0.72MPa and is throttled to 0.15MPa. Determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, (b) the isentropic efficiency of the compressor and (c) the coefficient of performance.
Consider a refrigrator that operates on the vapor compression refrigeration cycle with R-134a as the working fluid. The refrigerant enters the compressor as saturated vapor at 70 kPa, and exits at 1200 kPa and 90°C, and leaves the condenser as saturated liquid at 1200 kPa. The coefficient of performance of this refrigrator is
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.28 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of 420 W from the surroundings. The heat exchanger loses no heat to the environment. 26°C 42°C Condenser Expansion valve Evaporator OL Water 18°C 1.2 MPa 65°C Oin W in Compressor 60 kPa -34°C Determine the COP of the refrigerator. (You must provide an answer before moving on to the next part.) The COP of the refrigerator is 1.824 >
Find the rate at which heat is extracted from the refrigerated space.
A vapor-compression refrigeration machine uses refrigerant-134a as much as 2 kg/min with operating conditions leaving the evaporator at a temperature of -14°C and a condenser pressure of 0.8 Mpa. Determine the COP value and cooling load of the machine.
A vapor-compression cycle is used as a refrigerator to extract 8 kW of heat from a cold space at 0°C and rejects heat into a space at 25°C. R-134a enters the compressor at 140 kPa superheated by 4°C above the saturation temperature and leaves at 900 kPa. It exits the condensor as a saturated liquid. Assume that pressure losses are negligible and that the compressor is isentropic. Report your answers to four significant digits using rounding. QUESTION 1 Report the maximum possible COP. QUESTION 3 Report the power required by the compressor. QUESTION 2 Report the mass flow rate in kg/s. QUESTION 4 Report the COP for the cycle.
A gas refrigeration system utilizing air as the working fluid possesses a pressure ratio of 3. The air is directed into the compressor at 5°C. The high- pressure air is then cooled down to 40°C by rejecting heat to the ambient environment. The refrigerant exits the turbine at -85°C and subsequently absorbs heat from the cooling area prior to its entry into the regenerator. The mass flow rate of air is 0.45 kg/s. Given that the isentropic efficiencies are 82 percent for the compressor and 87 percent for the turbine, and using constant specific heats at ambient temperature, find: (a) The effectiveness of the regenerator. (b) The rate at which heat is extracted from the cooling area. (c) The Coefficient of Performance (COP) of the cycle.
A vapor compression refrigerator using R134a as the refrigerant operates under the following conditions: The refrigerant condenses at 50°C and is then sub-cooled by 10°C to 30°C before expansion. After an isenthalpic expansion, the refrigerant evaporates at -20°C and then superheated by 10°C to 0°C before compression. The refrigerant is compressed to 70°C with entropy of 1.0 kJ/kg.K at the end of the compression. a)With reference to the above operating conditions, draw the cycle on the R134a p-h diagram. b)Calculate the specific refrigerating effect at the evaporating temperature of -20°C. c)Calculate the work input for the compression process. d)Prove the vapor compression is not an isentropic process. e) Calculate the COP of the cycle. f)To produce 5kW cooling, what is the refrigerant flow rate required?
Compressor as the core part of a domestic air conditioner is using Refrigerant-134a as ns working fluid. The refrigerant enters the compressor at 140 kPa and –13°C with the required power input of 120 kW, and it is compressed to the condenser pressure and temperature of 1000 kPa and 60°C respectively. Evaluate if the adiabatic compressor is able to deliver compressed air at a minimum rate of 5 kg/s. Justify your answer with relevant calculations.
Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, a) Show the cycle on a T-S diagram b) Determine the rate of heat removal from the refrigerated space and the power input to the compressor c) Determine the adiabatic efficiency of the compressor d) Determine the coefficient of performance of the refrigerator.