This application analyzes the following refrigeration cycle, and calculates the coefficient of performance.

Additionally, the thermodynamic cycle will be plotted on a pressure-enthalpy-temperature chart.

The compressor, condenser, throttle and evaporator are analyzed in sequence with this equation, a statement of the conservation of energy,

q - w= Δh + ΔKE + ΔPE

where

Consider the energy flows in the compressor.  For an adiabatic process, q = 0. Also ΔKE = 0 and ΔPE = 0. Hence -w =  Δh

Enthalpies at points 1 and 2

The work done by the compressor (w)

Pressure at point 1

For the condenser, w = 0, ΔKE = 0 and ΔPE = 0. Hence q = Δh

Enthalpy at point 3

For the throttle, q = 0, w = 0, ΔKE = 0 and ΔPE = 0. Hence Δh = 0

Enthalpy at point 4

Saturation pressure of R134a at 253 K

Quality at  P = press4 and H = h4

For the evaporator, w = 0, ΔKE = 0 and ΔPE = 0. Hence q = Δh

Heat extracted by evaporator