HJD Institute of Technical Education and Research
Kera-Kutch
Department of Mechanical Engineering
REFRIGERATION AND AIR-CONDITIONING
ASSIGNMENT -1
Q1. A machine working on Carnot cycle operates between 305 k and 206 k. determine the
COP when it is operated as 1. A refrigerating machine; 2.heat pump; and 3. Heat engine.
Q2. 1.5KW per ton refrigeration is required to maintain the temperature of -40o c in the
refrigerator. If the refrigeration cycle works on Carnot cycle, determine the following:
1, COP of the cycle; 2, temperature of the sink: 3, Heat rejected to the sink per tonne of
refrigeration; and 4, heat supplied and EPR if the cycle is used as a heat pump.
Q3.the capacity of a refrigerator is 200 TR when working between -60C and 25oC. Also find
the power required to drive the unit. Assume that cycle operates on reversed Carnot
Cycle and latent heat of ice is 335 KJ/kg.
Q4, 500 kg of fruits are supplied to a cold storage at 20 oC. The cold storage is maintained at 50C and the fruit get cooled to the storage temperature in 10 hr. the latent heat of
freezing is 105 kj/kg k . Find the refrigeration capacity of the plate.
Q5, A refrigerator working on bell-Coleman cycle operates between pressure limits of 1.05
bars and 8.5 bar. Air is drawn from the cold chamber at 100C, compressed and then it is
cooled to 30oC before entering the expansion cylinder. The expansion and compression
follows the law pv1.3 =constant. Determine the theoretically COP of the system.
Q6, air refrigeration used for food storage provides 25TR. The temperature of air entering
the compressor is 7oC and the temperature at exit of cooler is 27oC. fiend :1, COP of cycle
and 2, power per tonne of refrigeration required by the compressor. The quantity of air
circulated in the system is 3000 kg/h. The compression and expansion both follows the
law pv1.3= constant and take γ=1.4 and cp= 1 kj/kg K for air.
Q7, a density of air refrigeration cycle operates between pressures of 4 bar and 16 bar. The
air temperature after heat rejection to surroundings is 37 oC and air temperature at exit
of refrigerator is 7oC, the isentropic efficiencies of turbine and comperation are 0.85 and
0.80 respectively. Determine compressor and turbine word per TR; COP; and power per
TR. Take γ=1.4 and Cp=1.005 kj/kg K.
Mr NISHANT R.SHUKLA
(SUBJECT IN-CHARGE)
Mr N. J.PATEL
(H. O. D MECH DEPT)