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Handbook of air conditioning and refrigeration / Shan K

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REFRIGERANTS, REFRIGERATION CYCLES, AND REFRIGERATION SYSTEMS 9.27<br />

FIGURE 9.6 (a) Subcooling <strong>and</strong> (b) superheating.<br />

3. The coefficient <strong>of</strong> performance <strong>of</strong> this <strong>refrigeration</strong> cycle<br />

4. The mass flow rate <strong>of</strong> the refrigerant<br />

Recalculate the COP <strong>and</strong> the energy saved in work input if the refrigerant is subcooled to a temperature<br />

<strong>of</strong> 90°F (32.2°C).<br />

Solution<br />

1. From Eq. (9.20), the enthalpy <strong>of</strong> the saturated liquid refrigerant at a temperature <strong>of</strong> 95°F (35°C),<br />

point 3 as shown in Fig. 9.5a, is<br />

h 3 � h 4 � 10.409 � 0.26851T s � 0.0001479T s 2 � 5.3429 � 10 �7 T s 3<br />

� 10.409 � 0.26851(95) � 0.0001479(95) 2 � 5.3429 � 10 �7 (95) 3<br />

� 10.409 � 25.508 � 1.335 � 0.458 � 37.71 Btu / lb

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