Page 130 - Industrial Ventilation Design Guidebook
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92 CHAPTER 4 PHYSICAL FUNDAMENTALS
FIGURE 4.14 The energy-humidity borderline.
humid air flow are mxi and ri%X2 and they have an effect on the energy bal-
ance through terms h^ and h^ 2-
Correspondingly, the humidity or water balance is
In many cases the incoming and outgoing air flows can consist of vari-
ous air flows in different states (temperature, humidity), which must be
treated separately. This means that the air enthalpy flow must be divided
into corresponding parts.
Example 8
Mixing of two air flows. As illustrated in Fig 4.15^, the energy balance is
and the humidity balance is
The dry air balance is
From Eqs. (4.141 )-(4.143) it follows that
which shows that the mixing point is on the line connecting points 1 and 2 in
Fig 4.156.
Example 9
Heating of an air flow. From Eq. (4.139) it follows that
