Basics of Refrigeration — Winter 2022

Define Refrigeration. Give applications of refrigeration.

What is the unit of refrigeration in SI system? Explain 1 Ton of Refrigeration.

Give detailed classification of various refrigeration system.

What do you mean by COP? Explain in detail.

Derive the condition for maximum value of COP in case of Bell Coleman cycle.

Explain Carnot refrigeration cycle with P-Vand T-Sdiagrams and derive its COP.

Adense air refrigerator operating on Bell-Coleman cycle works between bar and 15 bar. The temperature of air after the evaporator and after cooler is 5°Cand 20°Crespectively. The evaporator extracts 2000 kJ/min of heat from the space to be cooled. Calculate (1) amount of air required in the cycle per minute, (2) power required to run the system, (3) COP and (4) mass flow rate of water per minute in cooler if rise in temperature of water is 20°C. Assume isentropic compression and expansion, Cp=1.008 kJ/kg K, γ=1.4 for air and for water Cp=4.18 kJ/kg K.

Explain Bell-Coleman refrigeration cycle with P-Vand T-Sdiagrams and derive its COP.

Arefrigerator unit working on bell-Coleman cycle takes air at -10°Cand compress it from 1bar to 6.5 bar with compression index of 1.2. The compressed air is cooled to a temperature 5°Cabove the ambient temperature of 25°Cbefore it is expanded in the expander where the index of expansion is 1.35. Determine: (1) COP (2) capacity of plants in ton of refrigeration (3) quantity of air circulated per minute for production of 2000 kg of ice per day at 0°Cfrom water at 20°C.

Explain standard VCR system with schematic diagram. Also draw p-h diagram for the same.1

Avapour compression refrigerator uses methyl chloride (R-40) and operates between temperature limits of -10°Cand 45°C. At entry to the compressor, the refrigerant is dry saturated and after compression it acquires a temperature of 60°C. Find the C.O.P. of the refrigerator. The relevant properties of methyl chloride are as follows

Explain effect of sub cooling and super heating on the performance of VCR system.

Arefrigeration machine using R-12 as refrigerant operates between the pressures 2.5 bar and 9 bar. The compression is isentropic and there is no undercooling in the condenser. The vapour is in dry saturated condition at the beginning of the compression. Estimate the theoretical coefficient of performance. If the actual coefficient of performance is 0.65 of theoretical value, calculate the net cooling produced per hour. The refrigerant flow is 5 kg per minute. Properties of refrigerant are:

Explain House hold refrigerator with neat sketch.

Explain construction and working of NH -H O VAR system with neat32 sketch.

Differentiate between wet compression and dry compression.

Explain construction and working of LiBr-H O VAR system with neat2 sketch. ****** ALL THE BEST