Question

In a simple vapour compression refrigeration plant, in which compressor inlet is dry saturated, the enthalpy at the inlet of bot compressor and evaporator are $1426kJ/kg$ and $347.5kJ/kg$. Mass flow rate, relative efficiency and maximum COP are $0.02kg/s,60$% and $5$ respectively. What is the work input to the compressor?

• A. $7.2kW$
• B. $8.2kW$
• C. $4.3kW$
• D. $10kW$

Answer 1

The correct option is A $7.2kW$

Refrigeration capacity, $RC=\dot{m}(h_1-h_2$)

$RC=0.02(1426-347.5)$

$RC=21.57kW$

${\eta }_{relative}=\frac{\text{Actual COP}}{\text{Maximum COP}}=\frac{(COP{)}_{actual}}{5}$

$(COP{)}_{actual}=5\times 0.6$

$COP{)}_{actual}=3$

$(COP{)}_{actual}=\frac{\left(RC\right)}{W}$

$W=\frac{21.57}{3}$

$W=7.19\simeq 7.2kW$