Refrigeration and Air conditioning — Winter 2023

Define 1) C.O.P. 2) Ton of Refrigeration. 3) Refrigerant.

Enlist Different (any eight) Methods of cooling.

Asimple air refrigeration system is used for an airplane to take 20 tons of refrigeration load. The ambient air conditions are 200C and 0.9 bar. The ambient air is rammed isentropically to a pressure of 1 bar. The air leaving the main compressor at pressure 3.5 bar. Temperature of air after cooler is 88.7 0C. Cabin is to be maintained at a temperature of 250C and a pressure of 1.05 bar. If the internal efficiency of the compressor is 80% and that of turbine is 75%. determine 1)Mass of air bled off the main compressor. 2)C.O.Pof the refrigeration system.

Compare VCR (vapour compression refrigeration) and VAR (vapour absorption refrigeration).

Compare H O-NH and LiBr-H Ovapour absorption refrigeration system.232

Explain with neat sketch “Cascade Refrigeration system”.

Explain with diagram “Multiple evaporators with back pressure valves and with multiple expansion valves without flash inter cooling refrigeration system.

Which are the desirable properties of refrigerant-absorbent pair.

Explain with neat sketch “Electrolux Refrigeration system”.

With neat sketch, explain working of Thermostatic expansion valve.

Explain how problems of window air conditioner are mitigated by split air conditioning system?

Explain with neat sketch “Practical H O -NH cycle”.23

With neat sketch explain working of “evaporative condenser”.

Define -Effective temperature.

State different sensible heat load of building.(any four)

State and explain various heat load to be considered for cooling load calculation of an automobile.

Define thermal comfort and state factors affecting thermal comfort.

State importance of flywheel effect in designing of building air-conditioning system.

Explain following by use of supporting formula. 1)Sensible heat gain through building structure by conduction. 2)Load due to air infiltration. 3)Load due to electric motor.

Give classification of air conditioning system.

Explain with neat sketch “Summer air conditioning system”.

Aduct of 15 m length passes air at the rate of 90 m3/min. Assuming the friction factor as 0.005, calculate the pressure drop in the duct in mm of water when (a) the duct is circular of diameter 0.3 m; and (b) the duct is 0.3 m square cross section.

Compare, Package air conditioning system and Central air conditioning system.

Explain with neat sketch “Winter air conditioning system”.

Arectangular duct section of 500 mm x 350 mm sizes carries 75 m3/min of air having density of 1.15 kg/m3.Determine the equivalent diameter of a circular duct if (a) the quantity of air carried in both the cases is same, and (b)the velocity of air in both the cases is same. If f =0.01 for sheet metal, find the pressure loss per 100 m length of duct.