Consider a two-stage cascade refrigeration system operating between the pressure limits of 2 MPa and 0.05 MPa. Each stage operates on an ideal vapor-compression refrigeration cycle with R-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where both streams enter at 0.5 MPa. If the mass flow rate of the refrigerant through the upper cycle is 0.25 kg/s, What would the COP

Consider a two-stage cascade refrigeration system operating between the pressure limits of 2 MPa and 0.05 MPa. Each stage operates on an ideal vapor-compression refrigeration cycle with R-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where both streams enter at 0.5 MPa. If the mass flow rate of the refrigerant through the upper cycle is 0.25 kg/s, What would the COP

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...

See similar textbooks

Similar questions

What are the approximate temperature ranges tor low-, medium-, and high-temperature refrigeration applications?
Consider a two-stage cascade refrigeration system operating between the pressure limits of 0.8 and 0.14 MPa. Each stage operates on the ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where both streams enter at about 0.4 MPa. If the mass flow rate of the Refrigerant through the upper circle is 0.24 kg/s, determine (a)the mass flow rate of the refrigerant through the lower cycle, (b)the rate of heat removal from the refrigerated space and the power input to the compressor, and (c)the coefficient of performance of this cascade refrigerator. Answers: (a) 0.195 kg/s, (b) 34.2 kW, 7.63 kW, (c) 4.49
Consider a two-stage cascade refrigeration system operating between the pressure limits of 0.8 and 0.14 MPa. Each stage operates on the ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counter-flow heat exchanger where both streams enter at about 0.4 MPa. If the mass flow rate of the refrigerant through the upper cycle is 0.24 kg/s, determine (a) the mass flow rate of the refrigerant through the lower cycle, (b) the rate of heat removal from the refrigerated space and the power input to the compressor, (c) the coefficient of performance of this cascade refrigerator, and (d) the intermediate pressure of the cascade cycle. For full credit, accurately, neatly draw the cascade system on an electronic PDF p-h diagram. Please only solve part d. If possible, show the ph diagram
1. Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.2 MPa and 200 kPa with refrigerant-134a as the working fluid.Heat rejection from the lower to the upper cycle takes place in a countercurrent adiabatic heat exchanger where the pressures in the upper and lower cycles are 0.4 and 0.5 MPa, respectively. In both cycles the refrigerant is a saturated liquid at the condenser outlet and a saturated vapor at the compressor inlet, and the isentropic efficiency of the compressor is 80 percent.The mass flow rate of the refrigerant in the lower cycle is 0.15 kg/s.Determine the following:a) the mass flow of the refrigerant through the upper cycle,b) the rate of removal from the refrigerated space andc) the COP of this refrigerator.d) Draw the T-s graph of the complete system and the diagram with all the components and processes of both cycles, indicate all the states in both cases (1, 2, 3….)
Consider a two-stage compression refrigeration system operating between the pressure limits of 0.8 and 0.14 MPa. The working fluid is refrigerant-134a. The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.4 MPa. Part of the refrigerant evaporates during this flashing process, and this vapor is mixed with the refrigerant leaving the low-pressure compressor. The mixture is then compressed to the condenser pressure by the high-pressure compressor. The liquid in the flash chamber is throttled to the evaporator pressure, and it cools the refrigerated space as it vaporizes in the evaporator. Assuming the refrigerant leaves the evaporator as saturated vapor and both compressors are isentropic, determine (a)the fraction of the refrigerant that evaporates as it is throttled to the flash chamber, (b)the amount of heat removed from the refrigerated space and the compressor work per unit mass of refrigerant flowing through the condenser,…
Consider a two-stage compression refrigeration system operating between the pressure limits of 1.2 MPa and 0.16 MPa. The working fluid is refrigerant-134a. The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.7 MPa. Part of the refrigerant evaporates and the remainder is mixed with the refrigerant leaving the low-pressure compressor. The mixture is then compressed to the condenser pressure by the high-pressure compressor. The liquid in the flash chamber is throttled to the evaporator pressure, and it cools the refrigerated space as It vaporizes in the evaporator. Assume that the refrigerant leaves the evaporator as saturated vapor and both compressors are isentropic. a) i) Determine the amount of heat removed from the refrigerated space ii) Determine the compressor work per unit mass of refrigerant flowing through the condenser b) Determine the coefficient of performance
Consider a two-stage compression refrigeration system operating between the pressure limits of 1.2 MPa and 0.16 MPa. The working fluid is refrigerant-134a. The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.7 MPa. Part of the refrigerant evaporates and the remainder is mixed with the refrigerant leaving the low-pressure compressor. The mixture is then compressed to the condenser pressure by the high-pressure compressor. The liquid in the flash chamber is throttled to the evaporator pressure, and it cools the refrigerated space as It vaporizes in the evaporator. Assume that the refrigerant leaves the evaporator as saturated vapor and both compressors are isentropic. a) Draw the 'T-S' Diagram and state the assumptions b) Determine the fraction of the refrigerant that evaporates as it is throttled to the flash chamber (x_e).
Problem 1 (Using thermodynamic tables)A large refrigeration plant is to be maintained at -12 C. It requires refrigeration at a rate of 120 kW.The condenser of the plant is to be cooled by liquid water, which experiences a temperature rise of 10 C as it flows over the coils of the condenser. Assuming the plant operates on the ideal vapor-compression cycle using refrigerant- 134a between the pressure limits of 100 and 700 kPa, determine (a) the mass flow rate of the refrigerant, (b) the power input to the compressor, and (c) the mass flow rate of the cooling water
Consider a two-stage cascade refrigeration system operating between -80 o C and 80 o C. Each stage operates on an ideal vapor-compression refrigeration cycle. Upper cycle use R-12 as working fluid, lower cycle use R-13. In the lower cycle refrigerant condenses at 0 o C, in the upper cycle refrigerant evaporates at -5 o C. If the mass flow rate in the lower cycle is 1 kg/s, determine the mass flow rate through the upper cycle. Group of answer choices 1.56 kg/s 2.46 kg/s 1.78 kg/s 2.30 kg/s
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
x = 4 and y = 9, Consider a two-stage cascade refrigeration system operating between the pressure limits of 0.8 and 0.1x MPa. Each stage operates on the ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where both streams enter at about 0.4y MPa. If the mass flow rate of the refrigerant through the upper cycle is 0.24 kg/s, determine: (a) Sketch T-s diagram by listing all the entry and exit points to each refrigeration equipment as well as labelling the pressure lines, (b) the mass flow rate of the refrigerant through the lower cycle, (c) the rate of heat removal from the refrigerated space and the power input to the compressor, (d) the coefficient of performance of this cascade refrigerator. Calculate the work done by a single compressor if it is to deliver the cooling load as above by compressing refrigerant-134a from 0.1x MPa to 0.8 MPa.…
Consider a two-stage cascade refrigeration system operating between 0.1MPa and 1MPa. Each stage operates on the ideal cycle with R-134a as the working fluid. Heat rejection from the lower to the upper cycle occurs at 0.4MPa. If the mass flow rate in the upper cycle is 0.1 kg/s, Determine:(a) the mass flow rate through the lower cycle and (b)the COP.