Adiabatic operations humidification

The use of these relationships in constructing and applying humidity charts is best illustrated by examining a simplified case, that of adiabatic cooling or humidification. Figure 5.4 illustrates this process between air and water that is recycled through the cooling tower. In this operation air is both cooled and... 

This result (which is far from obvious) allows us to perform adiabatic cooling calculations with relative ease using the psychrometric chart. First locate the initial state of the air on the chart then locate the final state on the constant wet-bulb temperature line that passes through the initial state (or on the 100% humidity curve if cooling below the adiabatic saturation temperature takes place) and finally perform whatever material and energy balance calculations are required. Example 8.4-7 illustrates such a calculation for an adiabatic humidification operation. 

A complete justification of the procedure given above is beyond the scope of this text, but we can at least offer a partial explanation. A flowchart of an adiabatic cooling operation is shown below. A stream of warm air and either a stream of liquid water (spray cooling or spray humidification), a wet solid (drying), or a solid suspension (spray drying) are brought into contact. The air enters at T and leaves at Ts, the water and any solids enter at Tj and leave at T, and entering liquid water evaporates at a rate mwe(kg/s). 

IliustradoD 7.13 A horizonlal spray chamber (Fig. 7.19) with recirculated water is used for adiabatic humidification and cooling of air. The active part of the chamber is 1 m long and has cross section of 2 m. With an air rate 3.5 mV at dry-bulb temperature 65.0 C, Y 0.0170 kg water/kg dry air, the air is cooled and humidified to a dry-bulb temperature 42.0 C. If a duplicate spray chamber operated in the same manner were to be added in series with the existing chamlUr, what outlet conditions could be expected for the air ... 

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