Environmental Engineering Reference
In-Depth Information
Figure 16.5.8 Actual view of the open-cycle liquid desiccant air-conditioning system showing the
absorber/dehumidifier (1), desorber/regenerator (2); air ducts (3), fan (4), rotary air/air
heat exchanger (5), control cabinet (6), solar collector field (7) and hot water storage
tank (8) (Gommed and Grossman, 2007).
An open-cycle liquid desiccant air-conditioning system was installed at the Energy
Engineering Centre at the Technion, in the Mediterranean city of Haifa, as depicted
in Figure 16.5.8 with schematic diagram presented in Figure 16.5.9 (Gommed and
Grossman, 2007). The system uses solar energy for regeneration, with thermal and
chemical storage tanks (hot water and absorbent). The analysis of the system revealed
a thermal COP of approximately 0.8 with a parasitic loss of around 10%. Based on the
analysis, parasitic losses could be minimized with an improvement of the overall COP.
A liquid desiccant system was installed at the Energy Park of the Asian Institute
of Technology (AIT) in Pathumthani, Thailand (Katejanekarn et al., 2009). Figure
16.5.10 shows the actual installation of the solar-regenerated absorbent ventilation pre-
conditioning system, while Figure 16.5.11 shows the schematic of the installed system.
Results from the study showed that the solar open-cycle absorbent air-conditioning
system can work in tropical climates like that of Thailand. The humidity of outdoor
air can be reduced by 11%, while the temperature of the supply air is almost the same
as the outdoor air. This means that an auxiliary air-cooling system is still needed to
control the air temperature. Zhao et al. (2012) reviewed the open-cycle absorbent
air-conditioning system in a 21,960 m 2 building in Shenzhen, China. The system can
provide the required indoor thermal comfort and air quality based on temperature,
humidity and CO 2 concentration. With a COP of 4.0, the system is much better than
an ordinary AC system.
In Singapore, modern applications of liquid-based and solid-based desiccants are
used in AC systems in commercial buildings. In one example where 540 m 2 solar hot
water collector panels are used to support a 3000 m 2 factory hall using liquid-desiccant
air-conditioning, the annual energy saving amounted to S$ 50,000 (Singapore Liquid
Desiccant).
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