Determine capacity of the plant:

An R12 refrigeration system works among pressure limits 1.83 bar & 9.63 bar respectively. The heat transfer through the condenser is 80 kJ/min. The refrigerant vapour leaves the evaporator in the saturated state. The condensate leaves the condenser in only saturated state. The refrigerant pass through the system is found to be 0.6 kg/min. determine a) COP, b) capacity of the plant & c) the energy input to the compressor.

Solution

From the saturation property tables or p-h diagram, the enthalpies are attained as:

 h₁ = 181.94 kJ/kg, h₄ = 74.77 kJ/kg

 The refrigerating effect is found from following:

q_c =h₁ - h₄  = 181.94 - 74.77 = 107.17 kJ/kg

 Then,

From the first law:

The -ve sign indicates work input to the compressor.

 (a) 

 (b)  

(c)