Refrigeration Cycle
The below figure describes a refrigeration cycle using R-12a and its associated enthalpies. What is the coefficient of performance (COP)?
Hint
$$$COP=\frac{h_1-h_4}{h_2-h_1}$$$
Hint 2
Since this is a refrigeration cycle,
$$h_4=h_3$$
.
$$$COP=\frac{h_1-h_4}{h_2-h_1}$$$
Note that
$$h_4=h_3$$
due to the fact this is a refrigeration cycle. Thus,
$$$COP=\frac{(400-250)}{(440-400)}\cdot \frac{kJ/kg}{kJ/kg}=\frac{150}{40}=3.75$$$
3.75