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.) QH 750 kPa Condenser Expansion valve Evaporator QL 800 kPa 50°C in 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.) QH 750 kPa Condenser Expansion valve Evaporator QL 800 kPa 50°C in 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 [ %.

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

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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 >
Required information Refrigerant-134a enters the condenser of a steady-flow Carnot refrigerator as a saturated vapor at 65.0 psia, and it leaves with a quality of 0.05. The heat absorption from the refrigerated space takes place at a pressure of 30 psia. Determine the coefficient of performance. (Round the final answer to three decimal places.) The coefficient of performance 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 ↑ 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 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
42. Refrigerant-12 enters the condenser of a vapor-compression refrigera- tion system at 175 psia and 140°F and leaves as saturated liquid at 120°F. Mass flow rate of the refrigerant is 4.8 lbm/min. The heat is rejected to the surrounding air, which is at 90°F. Determine: (a) Heat rejection rate, Btu/hr. 22 (b) Separate the overall entropy changes per hour (Freon and sur- roundings). 23/
Question 3 In a vapour-compression refrigeration system, refrigerant - 134a enters the compressor superheated at 200 kPa and - 5 °C. The refrigerant enters the condenser at 1.4 MPa and 75 °C, and exits at 1.4 MPa as a saturated liquid. There is no significant heat transfer between the compressor and its surroundings, and the refrigerant passes through the evaporator with a negligible change in pressure. If the refrigerating capacity is 105 kW, represent the cycle on a T-s diagram and determine: a) the mass flow rate of the refrigerant in kg/s, b) the power input to the compressor in kW, c) the coefficient of performance, and (2) d) the isentropic compressor efficiency
An ammonia refrigerating system has a load of 250 kW and operates at a condensing pressure of 1400 kPa and an evaporating temperature of -20°C. The refrigerant exits at the evaporator with a 5- degree superheat. The vapor enters the compressor suction at 10-degree superheat. The compressed vapor is discharged from the compressor at the condensing pressure and 150°C. The refrigerant exits the condenser as saturated liquid. a. State the enthalpies at each point: Point enthalpy kJ/kg h kJ/kg kJ/kg h2 kJ/kg h3 kJ/kg h4 Answer: kg/sec b. Calculate the mass flow of refrigerant Answer: kW C. Determine the size of the motor drive if the mechanical efficiency of the motor- compressor is 77%. Answer: kW Calculate the total heat rejected in the condenser. d. Determine the refrigerating efficiency of the system. Answer: е.
In a vapor-compression refrigeration cycle, 9 kg/min of ammonia exits the evaporator as saturated vapor at-12°C. The refrigerant enters the condenser at 16 bar and 140C, and saturated liquid exits at 16 bar. There is no significant heat transfer between the compressor and its surroundings, and the refrigerant passes through the evaporator with a negligible change in pressure. Determine the refrigerating capacity, in kW. kW %3D Determine the power input to the compressor, in kW. kW %3D
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
A single-effect falling-film evaporator is used to concentrate orange juice from 14% to 45% solids. The evaporator utilizes a mechanical refrigeration cycle using ammonia as a refrigerant for heating and for condensing the vapors. The refrige-ration cycle is operated at a high-side pressure of 200 psia (1.379 MPa) and a low-side pressure of 50 psia (344.7 kPa). The evaporator is operated at a vapor temperature of 90oF (32.2oC). Feed enters at 70oF (21.1oC). The ratio of insoluble to soluble solids in the juice is 0.09, and the soluble solids consist of glucose and sucrose in 70:30 ratio. Consider the ΔT as the log mean ΔT between the liquid refrigerant temperature and the feed temperature at one point and the hot refri-gerant gas temperature and the concentrated liquid boiling temperature at the other point. The evaporator has a heat transfer surface area of 100 ft2 (9.29 m2), and an overall heat transfer coefficient of 300 BTU (h.ft2.oF) or 1073 W/(m2.K) may be expected. Calculate:…
Working fluid is Refrigerant 134a. Vapor-compression refrigeration system has refrigerating capacity = 1650 Btu/hour. Refrigerant enters evaporator at -10F and leaves at 15F. Isentropic compressor efficiency = 74%. Refrigerant condenses at 140F and leaves condenser subcooled at 100F. No large pressure drops through evaporator and condenser. DETERMINE: 1. Pressure of evaporator in lbf/in^2 2. Pressure of condenser in lbf/in^2 3. Mass flow rate in lb/s of refrigerant 134a. 4. Power input in horsepower of compressor. 5. Coefficient of performance.
Question 2: (a) The pressure at which the steam should be reheated. (b) The thermal efficiency of the cycle. (c) Total heat input (Qin) (d) Total turbine work output (Wtur.out) (e) Draw the T-S diagram Notes: Assume the steam is reheated to the inlet temperature of the high-pressure turbine. • The moisture content of the steam at the exit of the low-pressure turbine is not to exceed 9.5% Boiler 650 C 17.5 MPa ww Reheater High-P turbine P₁ = Ps= Preheat Pump Low-P turbine Condenser e 15 KPa