Active Thermal Cooling Technologies - Low Energy Cooling for Sustainable Buildings - page 132

Figure 5.15 Schematic of the desiccant cooling unit in the factory in Althengstett, Germany
5.2.2 Desiccant Cooling System in the Althengstett Factory
A desiccant cooling unit with a similar-sized air collector field of 100m 2 was built
for a plastics factory climatization in Althengstett, Germany (see Figure 5.15). The
air collector field consists of two parallel strings each with 50 m 2 of series connected
collectors, orientated towards the south-west with an azimuth angle of 232 ◦ and a tilt
angle of 30 ◦ . The air collector type is the same as the Spanish collector with flow
channels 9.5 cm high. The desiccant technology used is a lithium chloride sorption
wheel and auxiliary energy is provided by a heating system. The process volume flow
is 18 000m 3 h − 1 and regeneration air flow is at 11 000m 3 h − 1 . In addition to the rather
small air collector field for regeneration air heating, 45 kW of heat can be recovered
from the plastics machine coolers. In order to limit the specific volume flow through
the collectors, the regeneration air flow is only partially heated by the air collectors
with a maximum volume flow of 6000m 3 h − 1 . The air collector heat can also be used
directly to heat an older part of the factory, which is not insulated and often requires
heating even during the summer months.
Control Strategy
The main cooling loads within the factory are internal loads from the production
machines so that the desiccant cooling unit is mostly on when there is a produc-
tion run. The process and exhaust air volume flows are constant at 18 000m 3 h − 1 ,
and the regeneration volume flow is set to 11 000 m 3 h − 1 . If the room temperature