Question

A heat pump operates on the ideal vapor compression refrigeration cycle with R-134a. The condenser pressure is 1.2 MPa and the specific enthalpy at the inlet to condenser is 279 kJ/kg. If the mass flow rate of the refrigerant is 0.193 kg/s, the rate of heat supply to the heated space is

answer is 31.1 kw

Answer 1

In ideal vapor compression refrigeration cycle ,

  

Warm Environmet Qh Saturated liquid '- Condenser 2

Rate of Heat supply to heated space is $\dot{Q_{h}}$ given by,

  $\dot{Q_{h}}=\dot{m}(h_{1}-h_{2})$ -------(1)

from R134a properties table we can get the enthaly values

at inlet of condenser:

  $h_{1}=279kJ/kg$

at outlet of condenser :

refrigerant leaved as saturated liquid from condenser

at 1.2 MPa condenser pressure

$=>h_{2}=117.8kJ/kg$

From equation-(1) we can get

$=>\dot{Q_{h}}=\dot{m}(h_{1}-h_{2})$

$=>\dot{Q_{h}}=0.193(279-117.8)$

  $\dot{Q_{h}}=31.1116 kW$

So Rate of heat supply to the heated space is 31.1kw