Warehouse uses a refrigeration system (see figure) to keep farm produce at 2 ̊C while the temperature outside the warehouse is 30 ̊C. The produce and the outside air act as thermal reservoirs in this process. Although the warehouse is insulated, it absorbs heat from the surroundings at a rate of 775 kW. The condenser operates at 1.6 MPa and the evaporator operates at 300 kPa. Using ammonia as the working material, answer the following: b) Determine the power requirement of compressor in KW (c) Determine the COP for a Carnot refrigeration cycle (d) Determine the actual COP of the refrigeration cycle

Warehouse uses a refrigeration system (see figure) to keep farm produce at 2 ̊C while the temperature outside the warehouse is 30 ̊C. The produce and the outside air act as thermal reservoirs in this process. Although the warehouse is insulated, it absorbs heat from the surroundings at a rate of 775 kW. The condenser operates at 1.6 MPa and the evaporator operates at 300 kPa. Using ammonia as the working material, answer the following: b) Determine the power requirement of compressor in KW (c) Determine the COP for a Carnot refrigeration cycle (d) Determine the actual COP of the refrigeration cycle

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?

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Why is two-stage compression popular for extra-low-temperature refrigeration systems?
A supermarket warehouse uses a refrigeration system (see figure) to keep farm produce at 2 C while the temperature outside the warehouse is 30 C. The produce and the outside air act as thermal reservoirs in this process. Although the warehouse is insulated, it absorbs heat from the surroundings at a rate of 775 kW. The condenser operates at 1.6 MPa and the evaporator operates at 300 kPa. Using ammonia as the working material, answer the following: Condenser Expansion Valve Compresser Eveporator (a) Complete the Table below T (K) Р (КРа) н (к)/kg) S (kJ/kgK) State Phase of ammonia* 1 300 2 300 3 1600 4 1600 (b) Determine the power requirement of compressor in KW (c) Determine the COP for a Carnot refrigeration cycle (d) Determine the actual COP of the refrigeration cycle (e) Are you violating the second law of Thermodynamics? Please comment (f) Plot the T-S diagram for the refrigeration cycle
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 1 (3) Expansion valve Condenser Evaporator QL Water 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 6.273 ✪ KW.
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 ↑ 4 Condenser Expansion valve Evaporator QL Water 18°C 1.2 MPa 65°C ↑gin Win Compressor 60 kPa -34°C Determine the theoretical maximum refrigeration load for the same power input to the compressor. The theoretical maximum refrigeration load for the same power input to the compressor is KW.
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 >
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 I Condenser Expansion valve Evaporator QL Water 18°C 1.2 MPa 65°C Qin 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
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 Expansion valve 4 Condenser ↓ Evaporator Water 18°C QL 1.2 MPa 65°C Qin W in 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
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 3 Expansion valve 4 Condenser ↓ Evaporator Water 18°C OL (2) KW. (1 1.2 MPa 65°C ↑in 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
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. Water 26°C 18°C 1.2 MPa 42°C 65°C (2 t ein (3 Condenser Expansion valve in Evaporator Compressor 60 kPa -34°C 4 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
A chiller runs on R-410a as the working fluid. It operates with a condensing temperature of 45 C and an evaporating temperature of 0 C. It is determined to develop 85 kW of refrigeration. Calculate the following: (a)refrigerating effect, (b)flow rate of refrigeration, (c)power required by compressor, (d)coefficient of performance, (e)power per kilowatt of refrigeration, (f)theoretical horsepower input of the compressor
Avapour compression refrigeration system using refrigerant F-12 is employed to produce 8640 kg of ice per day. The condensing and evaporating temperature of refrigerant are 48°C and -20°C respectively. Saturated liquid leaves the condenser and saturated vapour leaves the evaporator. Compression is isentropic, water at 35 C is used to form the ice. The temperature of ice should be-8°C. Heat flow into the orme tank from surroundings may be taken as 10% of total heat absorbed from water to form ice. Determine the power required to drive the compressor. Take specific heat of ice = 2,26 kJ/kg-K. Latent heat of Ice= 335 kJ/kg. Specific heat of water = 4.2 kJ/kg-K.
The compressor of a refrigerator using refrigerant R134a draws 1.2 kW. Since the evaporation temperature in the evaporator is -22 °C and the condensation temperature in the condenser is 38 °C; (a) Plot this refrigerator system schematically with its elements and show it on the T-s and P-h diagram of the refrigeration cycle (b) The cooling power of the refrigerator (c) The amount of heat the refrigerator gives to the environment (d) Calculate the ideal and Carnot COP cooling values of this refrigerator.