Environmental Engineering Reference
In-Depth Information
Return air
Return air
Exhaust air
Return air Exhaust air
Return air
1
1
1
1
CMAU
AWheel
HT
RG
RG
2
2
4
4
4
HES
HES
HEAU
5
5
2
HES
HES
HES
HES
4
2
7
6
3
3
7
6
3
6
5
3
Supply
air
Exhaust
air
Supply
air
Exhaust
air
Supply
air
Exhaust
air
Supply
air
Exhaust
air
Ambient
air
Ambient
air
Ambient
air
Ambient
air
System 1
System 2
System 3
System 4
Figure 5.65
Schematics of the indirect supply air cooling system for the exhaust air humidification
(system 1), return air desiccant rotor (system 2), contact matrix absorber (system 3) and fully integrated
heat exchanger absorber unit (system 4). HES, water-sprayed heat exchanger; HT, heater; HEAU, heat
exchanger absorber unit; CMAU, contact matrix absorber unit; Awheel, desiccant rotor; RE, regeneration
unit
indirect evaporative cooling on the ambient air side, each liquid flowing parallel to
the air stream. A second cross-flow heat exchanger with evaporative cooling com-
bines the heat exchanger and evaporator so that only three instead of six components,
as shown in Figure 5.65, remain. The performance of such spray-cooled cross-flow
heat exchangers, with and without liquid sorption, is theoretically and experimentally
analysed in the following, using different salt solutions.
System Technology Options
Four different technological options for return air cooling were investigated with
increasing integration of components and improvement of performance, which are all
shown in Figure 5.65.
System 1
In the simplest reference cooling system available on the market, the
supply air is cooled by the return air in a cross-flow heat exchanger, which is sprayed
with water on the return air side for evaporative cooling. This water-sprayed cross-flow
heat exchanger combines the function of a humidifier and a heat exchanger. During
the humidification process of the return air in the water-sprayed heat exchanger, heat is
transferred from the supply air to the humidified return air. This allows the evaporation
of a greater amount of water, resulting in higher cooling performances compared with
systems with separated humidification and heat exchanging.
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