Active Thermal Cooling Technologies - Low Energy Cooling for Sustainable Buildings - page 180

Figure 5.68 Paths of return air dehumidification for different process options

32 ◦ C and 40% relative humidity. The results of the measurements taken at an air
volume flow of 200m 3 h − 1 are shown in Figure 5.68.
Path 1-2 describes the measured dehumidification process in the investigated des-
iccant rotor (AWheel) using regeneration air with a 12 g water kg − 1

air humidity ratio, at
70 ◦ C and volume flows of 187m 3 h − 1 . The humidity of the return air is reduced in the
desiccant rotor by about 4.3 g water kg − 1

air , while the temperature of the return air is in-
creased by about 19 ◦ C. This significant rise in temperature results from the adsorption
enthalpy and the heat transferred from the regeneration side.
Path 1-3, which indicates the dehumidification of the return air in the contact matrix
absorber unit (CMAU), shows a dehumidification of about 4.2 g water kg − 1

air combined
with an increase in the return air temperature of about 5 ◦ C. A part of the absorp-
tion enthalpy is removed by the liquid desiccant so that the process also reduces the
enthalpy.
Path 1-4 shows themeasured dehumidification of the return air in the heat exchanger
absorber unit (HEAU). The humidity is reduced by about 5.7 g water kg − 1

air , while the
temperature of the return air is decreased by about 1 ◦ C, that is, the process is just
slightly better than isothermal.
Path 5-6 shows the humidification and evaporative cooling process of the ambient
air in the cooling channels of the heat exchanger absorber unit. The humidification
process is also not isenthalpic. This is a consequence of the simultaneous removal of