Q31 An ideal vapor-compression refrigeration cycle works on R-12 and operates between (42 °C and -5C saturation conditions). the exit of the compressor (h₂) is at superheated conditions at 390 kPa and entropy S = 1.562 kJ/kg.K. 1- Draw the cycle on T-S diagram. 2- Calculate the refrigeration effect. 3- The heat removed to the environment. h2 S2 P2 12 P2= R3 51=32 17 marks) 4- The work supplied to the compressor. 52 = 5.1. R

Q31 An ideal vapor-compression refrigeration cycle works on R-12 and operates between (42 °C and -5C saturation conditions). the exit of the compressor (h₂) is at superheated conditions at 390 kPa and entropy S = 1.562 kJ/kg.K. 1- Draw the cycle on T-S diagram. 2- Calculate the refrigeration effect. 3- The heat removed to the environment. h2 S2 P2 12 P2= R3 51=32 17 marks) 4- The work supplied to the compressor. 52 = 5.1. R

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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With ph, ts diagram A refrigerator based on ideal vapor compression cycle operates between the temperature limits of -20 deg C and 40 deg C . The refrigerant enters the condenser as saturated vapor and leaves as saturated liquid . The enthalpy and entropy values for saturated liquid and vapor at these temperatures are given in the table below: T(OC) hf (KJ/kg) hg (KJ/kg) Sf (KJ/kg.K) Sg (KJ/kg.K) -20 20 180 0.07 0.7366 40 80 200 0.3 0.67 If the circulation rate of the refrigerant is 0.025 kg/sec , the refrigeration effect is equal to A) 1.2 kW B) 2.5 kW C) 3.2 kW D) 2.1 kW
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Q.13 A vapour compression refrigeration system using refrigerant F-12 is employed to produce 8640 kg of ice per day. The condensing and evaporating temperature of refrigcrant 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 brine 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 following data may be used: %3D Temp. Pressure Enthalpy Entropy °C bar kJ/lg kJ/kg-K Liquid Vapour Liquid Vapour 48°C 11.64 82.83 205.83 0.2973 0.6802 -20 1.51 17.82 178.74 0.0731 0.7087 Specific heat of vapour 0.82 kJ/kg %3D
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