4- A cascade refrigeration system of 14 TR uses Freon R-12 at -50 °C evaporating temperature and condensing temperature of -15°C with adiabatic compression efficiency of 85 %. The upper cycle uses NH3 with condensing temperature of 37 °C and compression efficiency of 90 %. The temperature difference between the evaporator of the upper cycle and the condenser of the lower cycle is 10 °C. Calculate the power required for each compressor if the mechanical efficiency is 90% and the C.O.P. of the unit.

4- A cascade refrigeration system of 14 TR uses Freon R-12 at -50 °C evaporating temperature and condensing temperature of -15°C with adiabatic compression efficiency of 85 %. The upper cycle uses NH3 with condensing temperature of 37 °C and compression efficiency of 90 %. The temperature difference between the evaporator of the upper cycle and the condenser of the lower cycle is 10 °C. Calculate the power required for each compressor if the mechanical efficiency is 90% and the C.O.P. of the unit.

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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Similar questions

Refrigerators currently being manufactured in the United States are using______as their refrigerant.
Condensers in these refrigerators are all_______cooled.
In an ideal vapour-compression refrigeration cycle, refrigerant R-12 enters the compressor as a saturated vapour at −18 degree C and leaves the condenser as a saturated liquid at 25 degree C. The mass flow rate of the refrigerant is 0.5 kg/s, and the pressure drop in the evaporator and the condenser are negligible. Calculate: a) the refrigeration effect (rate of refrigeration or heat transfer rate in the evaporator) b)power consumed by the compressor c)the coefficient of performance of the refrigerator) d)qualityof the refrigerant after the expansion valve e)heat transfer rate in the condenser
An ideal vapor-compression refrigeration cycle that uses refrigerant-134a as its working fluid maintains a condenser at 800 kPa and the evaporator at 15 kPa. Given 300 kW of cooling load, determine the following: 3. Estimate the reversible COP values, if the low and high medium temperature are as for the evaporator and condenser. 4. Determine the Refrigeration effect (RE), heat of compression (HOC), and heat of rejection (HOR) and their corresponding rate/power values in kW. 5. Estimate the COPR using thermodynamic tables 6. Calculate the COPR using the P-h chart and show the refrigeration cycle on the p-h chart.
A simple vapor - compression cycle develops 13 tons ofrefrigeration. Using ammonia as refrigerant and operating at acondensing temperature of 24 °C and evaporating temperature of-18°C and assuming that the compression are isentropic and thatthe gas leaving the condenser is saturated. Find the followinga). Draw the p-h diagramb.) Refrigerating effect in kJ/kgc.) Circulation flow in kg/mind.) Power requiremente.) Volume flow in cubic meter per minute per tonf.) Coefficient of performanceg.) Power per ton
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In a Refrigerant 12 system which serves a 212 kw evaporator at - 30 0C. The system uses two stage compression with intercooling and removal of flash gas. The condenser temp is 400C . Given that, h2=356kJ/kg, h4=367kJ/kg Compute the following: a.) mass flow rate at low stage compressor (m1)ANSWER: 1.53661 kg/s b.) mass flow rate at high stage compressor (m3)ANSWER: 2.11791 kg/s c.) low stage compressor workANSWER: 27.43931 kw d.) high stage compressor workANSWER: 32.63926 kw e.) total compressor workANSWER: 60.078575 kw f.) COPANSWER: 3.52871 g.) heat rejected in the condenserANSWER: 272.07857 kw
A two-evaporator, multiple EV,and multiple compression refrigeration system uses refrigerant-134a as the working fluid. The system operates evaporator 1 at 0°C, evaporator 2 at -26.4°C, and the condenser at 800kPa. The refrigerant is circulated through the compressor at a rate of 0.1kg/s and the low temperature evaporator serves a cooling load of 8 kW.Determine the cooling rate of the high-temperature evaporator, the power required by the compressor, and the COP of the system. The refrigerant is saturated liquid at the exit of the condenser and saturated vapor at the exit of each evaporator, and the compressor is isentropic.
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A refrigeration plant running on R-134a operates between saturation temperatures 0°C and 45°C andhas a refrigeration capacity of 1-MW. The vapour is dry saturated at entry to the compressor and there isno undercooling in the condenser. Taking an overall isentropic efficiency for the compressor of 0.8,calculate:3.1 The coefficient of performance,3.2 The required power input.