Consider a refrigeration system that operates on an actual vapor-compression refrigeration cycle with refrigerant 134a as the working fluid with an isentropic efficiency of a compressor of 75.1%. The refrigerant enters the compressor as saturated vapor at 140 kPa and is compressed to 800 kPa. Determine the value of h2 in kj/hg, answer in 4 decimal places with unit analysis.

Consider a refrigeration system that operates on an actual vapor-compression refrigeration cycle with refrigerant 134a as the working fluid with an isentropic efficiency of a compressor of 75.1%. The refrigerant enters the compressor as saturated vapor at 140 kPa and is compressed to 800 kPa. Determine the value of h2 in kj/hg, answer in 4 decimal places with unit analysis.

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?

See similar textbooks

Similar questions

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. 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.
Consider a 300 kJ/min refrigeration system that operates on an ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. The refrigerant enters the compressor as saturated vapor at 140 kPa and is compressed to 800 kPa. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the quality of the refrigerant at the end of the throttling process, (b) the coefficient of performance, and (c) the power input to the compressor.
Refrigerant-134a enters the compressor of a refrigerator at 140 kPa and -10°C at a rate of 0.3 m3/min and leaves at 1 MPa. The isentropic efficiency of the compressor is 78 percent. The refrigerant enters the throttling valve at 0.95 MPa and 30°C and leaves the evaporator as saturated vapor at -18.5°C. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the power input to the compressor, (b) the rate of heat removal from the refrigerated space, and (c) the pressure drop andrate of heat gain in the line between the evaporator and the compressor. answers 1.88 kW, 7.11 kW, 1.72 kPa, 0.24 kW
Consider a refrigeration system that operates on an actual vapor-compression refrigeration cycle with refrigerant 134a as the working fluid with an isentropic efficiency of a compressor of 83.4%. The refrigerant enters the compressor as saturated vapor at 140 kPa and is compressed to 800 kPa. Determine the value of h2 in kj/hg, answer in 4 decimal places with unit analysis. SUBJECT: Refrigeration Systems
The COP of vapor-compression refrigeration cycles improves when the refrigerant is subcooled before it enters the throttling valve. Can the refrigerant be subcooled indefinitely to maximize this effect, or is there a lower limit? Explain.
A refrigerator uses refrigerant-134a as the working fluid and operates on an ideal vapourcompression refrigeration cycle between 0.12 MPa and 0.7 MPa. The mass flow rate of therefrigerant is 0.05 kg/s. Show the cycle on a T-s diagram with respect to saturation lines.Determine;(a) The rate of heat removal from the refrigerated space and the power input to thecompressor,(b) The rate of heat rejection to the environment, and(c) The coefficient of performance.
A standard vapor compression system produces 70.4 kW of refrigeration using R-12as a refrigerant while operating between a condenser temperature of 42 °C and anevaporator temperature of –25 °C.2.1 Draw the p-h diagram of the cycle. 2.2 Determine:(a) the refrigerating effect in kJ/kg, (b) the circulating rate in kg/s, (c) the power supplied, (d) the COP, (e) the heat rejected in kW, and(f) the volume flow rate in m3/s.
A refrigerated room is kept at −18◦C by a vapor-compression cycle with R-134a as the refrigerant. Heat is rejected to cooling water that enters the condenser at 14◦C at a rate of 0.35 kg/s and leaves at 22◦C. The refrigerant enters the condenser at 1.2MPa and 50◦C and leaves at the same pressure subcooled by 5◦C. If the compressor consumes 5.5 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load and the COP, (c) the second-law efficiency of the refrigerator and the total exergy destruction in the cycle, and (d) the exergy destruction in the condenser. Take specific heat of water to be 4.18 kJ/kg·◦C.
Why is the reversed Carnot cycle executed within the saturation dome not a realistic model for refrigeration cycles?
Refrigerant 134a is the working fluid in a vapor- compression heat pump that provides 35 kW to heat a dwelling on a day when the outside temperature is below freezing. Saturated vapor enters the compressor at 1.6 bar, and saturated liquid exits the condenser, which operates at 8 bar. Determine, for isentropic compression: a- the refrigerant mass flow rate, in kg/s. b- the compressor power,in kW. c- The coefficient of performance. Recalculate the quantities in parts (b) and (c) for an isentropic compressor efficiency of 75%.
Consider the following ideal cascade refrigeration system with pressures of 0.9, 0.4, and 0.12 MPa.If the lower cycle transfers 69kW of energy to the upper cycle, determine the mass flowrate of R-134A (in kg/s) in the upper cycle. a.0.3987 b.0.4114 c.0.3600 d.0.4480
Consider a refrigeration system using refrigerant-134a as the working fluid. If this refrigerator is to operate in an environment at 20°C, what is the minimum pressure to which the refrigerant should be compressed? Why?