Fridge Cycle
The shown figure describes a refrigeration cycle using R-12a and its associated enthalpies. If the coefficient of performance (COP) is 2, what is the enthalpy (kJ/kg) at point 3?
Expand Hint
For a refrigeration cycle, the coefficient of performance is:
$$$COP_{ref}=\frac{h_1-h_4}{h_2-h_1}$$$
where
$$h$$
is the enthalpy.
Hint 2
For heat pumps and refrigeration cycles,
$$h_4=h_3$$
.
For a refrigeration cycle, the coefficient of performance is:
$$$COP_{ref}=\frac{h_1-h_4}{h_2-h_1}$$$
where
$$h$$
is the enthalpy.
For heat pumps and refrigeration cycles,
$$h_4=h_3$$
. Thus,
$$$2=\frac{(320kJ/kg-h_3)}{(425kJ/kg-320kJ/kg)}$$$
$$$h_3=320kJ/kg-(2)(105kJ/kg)=110\:kJ/kg$$$
110 kJ/kg
Time Analysis
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