Handbook of air conditioning and refrigeration / Shan K

15.82 CHAPTER FIFTEEN
FIGURE 15.47 Two-stage air washer using deep well water.
Groundwater can be used again as condenser water, or as flushing water in plumbing systems
after its discharge from the air washer following necessary water treatment. Used groundwater
should be drained to another well (recharge well) in the vicinity to prevent subsidence and damage
to the soil, which may affect the foundation of the building in the vicinity of the deep well.
The use of groundwater is regulated by local and federal environmental protection agencies.
15.22 CHARACTERISTICS OF ATOMIZING AND WETTED
ELEMENT HUMIDIFIERS
Atomizing and wetted element humidifiers, including air washers for humidification purposes have
the following operating characteristics:
● Conditioned air follows the thermodynamic wet-bulb temperature line on a psychrometric chart.
The humidity ratio of the air increases while it is evaporatively cooled. Atomizing humidifiers are
often called nonisothermal humidifiers. This characteristic indicates that atomizing and wetted
element humidifiers are especially suitable for conditioned spaces that need a cold air supply to
offset a space cooling load during or after the humidification process. The heat energy required to
evaporate the liquid water, as in steam or heating element humidifiers, has been saved. For a conditioned
space which needs a warm air supply during winter operation, the temperature of evaporatively
cooled air after an atomizing or wetted element humidification process should be raised before
supplying it to the conditioned space, so as to offset the transmission loss through the building envelope.
The heat energy required is approximately equal to that required to evaporate water in a steam
boiler or in a water pan when a steam humidifier or a heating element humidifier is used.
● For atomizing humidifiers that need a cold air supply during winter, when the humidifying
capacity is modulated, both the space relative humidity and temperature vary accordingly. Many