Compression Process:

The vapour refrigerant at low temperatureT₁ and pressure p₁ is compressed is entropic ally to dry saturated vapour as indicated through the vertical line 1-2 on the T-s diagram and through the curve 1-2 on p-h diagram. The pressure & temperature go up from p1 to p2 & T1 to T2 respectively.

The work done throughout isentropic compression per kg of refrigerant is given by

                                                                               w = h₂ - h₁

here  h₁ = Enthalpy of vapour refrigerant at temperature T₁, that means at suction of the compressor, & h₂ = Enthalpy of the vapour refrigerant at temperature T₂. That means at discharge of the compressor.