Refrigeration and Air Conditioning
A refrigerating system operating on reversed Brayton refrigeration cycle is used for maintaining 250 K. If the temperature at the end of constant pressure cooling is 300 K and rise in the temperature of air in the refrigerator is 50 K, then the net work of compression will be (assume air as working substance with Cp = 1 kJ/kg)

125 kJ/kg
50 kJ/kg
25 kJ/kg
100 kJ/kg

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Refrigeration and Air Conditioning
A good refrigerant should have

High operating pressures and low freezing point
Low C.O.P. and low freezing point
High specific volume and high latent heat of vaporisation
High latent heat of vaporisation and low freezing point

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Refrigeration and Air Conditioning
The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water, and T₃ = Evaporator temperature)

[T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)]
[T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)]
[T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)]
[T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)]

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