Handbook of air conditioning and refrigeration / Shan K

15.40 CHAPTER FIFTEEN
FIGURE 15.29 Dry coils at design and part-load operation.
Fs � coil core surface area parameter
Aa � face area of coil, ft2 (m2 )
Nr � number of rows in coil
�Tm � log-mean temperature difference, °F (°C)
m˙ w � mass flow rate of chilled water, lb/min [kg/(60 s)]
Twl, Twe � temperature of chilled water leaving and entering coil, °F (°C)
Because , here indicates the volume flow rate of chilled water, in cfm [m/(60 s)],
and �w � water density, which can be estimated as 62.32 lb/ft 3 . Also, 1 gal � 0.1337 ft3 m˙ w � V˙ w�w V˙ w
(3.785 L)
and cpw � 1, so
Q cs � 60V˙ w� w c pw(T wl � T we)
� 60 � 0.1337V˙ gal� w c pw(T wl � T we)
� 500V˙ gal(T wl � T we)
where V˙ gal � volume flow rate of chilled water, gpm (L/s)
Coil core surface area parameter Fs is defined as
F s � A o
A aN r
(15.25)
(15.26)