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.

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

Chapter3: Refrigeration And Refrigerants

Section: Chapter Questions

Problem 2RQ: What are the approximate temperature ranges tor low-, medium-, and high-temperature refrigeration...

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! Required information 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 0.29 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. 26°C 42°C Condenser Expansion valve Evaporator OL Water 18°C (~) 1.2 MPa 65°C Win Compressor 60 kPa -34°C Determine the quality of the refrigerant at the evaporator inlet. (Take the required values from saturated refrigerant-134a tables.) (You must provide an answer before moving on to the next part.) The quality of the refrigerant at the evaporator inlet is
! Required information 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 0.29 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. 26°C ↑ 42°C Condenser Expansion valve Evaporator OL Water 18°C 2 kW. 1.2 MPa 65°C W; in Compressor 60 kPa -34°C Determine the refrigeration load. (Take the required values from saturated refrigerant-134a tables and steam tables.) (You must provide an answer before moving on to the next part.) The refrigeration load is
Required information 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 0.29 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. 26°C 42°C Condenser Expansion valve Evaporator Water 18°C 1.2 MPa 65°C Qin Win Compressor 60 kPa -34°C Determine the quality of the refrigerant at the evaporator inlet. (Take the required values from saturated refrigerant-134a tables.) (You must provide an answer before moving on to the next part.) The quality of the refrigerant at the evaporator inlet is 7.57
Required information 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 0.29 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. 26°C 42°C ↓ Condenser Expansion valve Evaporator Q₁ Water 18°C 1.2 MPa 65°C lin Win Compressor 60 kPa -34°C Determine the refrigeration load. (Take the required values from saturated refrigerant-134a tables and steam tables.) (You must provide an answer before moving on to the next part.) The refrigeration load is kW.
Required information 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 0.29 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. 26°C 42°C ↓ Condenser 3 Expansion valve Water 18°C Evaporator QL (2) 1.2 MPa 65°C lin Win 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
Task 4 A heat pump using refrigerant-134a heats a house by using underground water at 8°C as the heat source. The house is losing heat at a rate of 60,000 kJ/h. The refrigerant enters the compressor at 280 kPa and 0°C, and it leaves at 1 MPa and 60°C. The refrigerant exits the condenser at 30°C. Determine (4) Calculate the COP of this heat pump (5) The increase in electric power input if an electric resistance heater is used instead of a heat pump (6) Investigate the effect of varying the compressor isentropic efficiency over the range [60 to 100 percent]. Plot the power input to the compressor and the electric power saved by using a heat pump rather than electric resistance heating as functions of compressor efficiency and discuss the results. (7) In order to increase the COP of the heat pump, what recommendations or improvements would you suggest? explain your recommendations.
3.) When a gas surrounded by air is compressed or expands adiabatically, its temperature rises or decreased even though there is no heat input or dissipated to the gas. Where does the energy come from to raise or lower the temperature? 4.) Why must a room air conditioner be placed in a window rather than just set on the floor and plugged in? Why can a refrigerator be set on the floor and plugged in?
! 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.) 750 kPa (3) Expansion valve 4 Он Condenser Evaporator Q₁ 800 kPa 50°C 2 1 Compressor Determine the isentropic efficiency of the compressor. (You must provide an answer before moving on to the next part.) The isentropic efficiency of the compressor is %.
! 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