A cold storage vapor compression refrigeration system operates with refrigerant R-134a. The specific enthalpies at key cycle states are: evaporator outlet $h_1 = 390.0\text{ kJ/kg}$, compressor outlet $h_2 = 425.0\text{ kJ/kg}$, and condenser outlet (before throttling) $h_3 = h_4 = 240.0\text{ kJ/kg}$. The Coefficient of Performance ($COP$) of the cycle is ________ (round off to two decimal places).
Answer Key:
4.29
Step-by-Step Solution & Explanation
The refrigerating effect ($RE$) is:
$RE = h_1 - h_4 = 390.0 - 240.0 = 150.0\text{ kJ/kg}$
The work of compression ($W$) is:
$W = h_2 - h_1 = 425.0 - 390.0 = 35.0\text{ kJ/kg}$
The Coefficient of Performance is:
$COP = \frac{RE}{W} = \frac{150.0}{35.0} = 4.29$