Page 126 - Industrial Ventilation Design Guidebook

88 CHAPTER 4 PHYSICAL FUNDAMENTALS

FIGURE 4.12 The state change of air in adtabatic humidification. A is the initial state and 8 is the sat-
urated final I state.

Using the notations in (4.132) we can without danger of mix-up leave out the
subscript 1 of the incoming point and write x\ = x and h kl = h k. Using these
notations and Eq. (4.131), Eq. (4.130) can be written as

So the state point of air in the Mollier diagram is shifted in a direction where
the dependency between the enthalpy and the humidity change according to
the Eq. (4.133) is valid. This result is illustrated in Fig. 4.12.
Equation (4.133) can be formally written in a form resembling Eq.
(4,123). To demonstrate this, we first write Eq. (4.133) as

On the other hand,

and

Substituting these into the equation above, we obtain by grouping terms
appropriately

On the other hand, the vaporization heat of water at temperature 0 ad is

and the specific heat of humid air per kilogram of dry air is