Handbook of air conditioning and refrigeration / Shan K

FIGURE 20.21 Adiabatic mixing and bypass mixing processes.
and m˙ 2 / m˙ m � (20.51)
hm � h1 �
h2 � h1 wm � w1 � K2 w2 � w1 where K 1, K 2 � fraction of airstreams 1 and 2 in the mixture.
From the above-mentioned relationships
1. The mixing point m must lie on the line that connects state points 1 and 2.
2. The ratio of the mass flow rate of airstream 1 to the mass flow rate of the mixture is exactly
equal to the ratio of segment m1-2 to segment 1-2, as shown in Fig. 20.21, that is,
(20.52)
Similarly, the ratio of the mass flow rate of airstream 2 to the mass flow rate of the mixture is
exactly equal to the ratio of segment m1-1 to segment 1-2, that is,
As the mass flow rate m˙ � V˙� , substituting into Eqs. (20.50) gives
AIR SYSTEMS: BASICS AND CONSTANT-VOLUME SYSTEMS 20.51
m˙ 1
m˙ m
m˙ 2
m˙ m
V˙ 1� 1h 1 � V˙ 2� 2h 2 � V˙ m� mh m
V˙ 1� 1w 1 � V˙ 2� 2w 2 � V˙ m� mw m
V˙ 1� 1 � V˙ 2� 2 � V˙ m� m
� m1-2
1-2
� m1-1
1-2
(20.53)
(20.54)