Environmental Engineering Reference
In-Depth Information
Regeneration
Exhaust air
Total heat
exchanger
Expansion valve
Return air
unit
Solution
pump
Condenser
Solution groove
Evaporator
Dehumidific-
action unit
Total heat
exchanger
Fresh air
Send air
Four-way
valve
Solution groove
Solution groove
Compressor
Plate heat exhanger
Figure 16.4.4 Schematic diagram of the hybrid open-cycle liquid desiccant air-conditioning system
with vapour compression system (Zhu et al., 2010).
produced 20% to 30% more cooling than the vapour compression system alone. Xiong
et al. (2010) also presented a novel open-cycle liquid desiccant air-conditioning system
with CaCl 2 . Compared to the basic system, the thermal coefficient of performance
and exergy efficiency of the system increased from 0.24% to 0.73% and from 6.8%
to 23.0% respectively. Khalid Ahmed et al. (1997), in a simulation model of the
hybrid open-cycle liquid desiccant air-conditioning system, showed that the system
provides an excellent alternative to conventional vapour absorption systems, particu-
larly in hot and humid climates. The COP obtained was about 50% higher than that
of a conventional vapour absorption system. A maximum COP of 1.25 was obtained
during the study and the unit was found to be best suited for hot and humid areas.
Figure 16.4.4 shows the hybrid open-cycle liquid desiccant air-conditioning system
with vapour compression system.
16.5 SYSTEM APPLICATION
16.5.1 Countries
Thermally operated desiccant air-conditioning technologies are a promising alternative
to the vapour compression system in handling air sensible and latent energy contents.
This is due to the possibility of operating the system by energy sources other than
fossil fuel-based electricity - solar energy, waste heat, etc. Research into the solar
desiccant ventilation and air-conditioning system is very important owing to the fact
that the amount of air thermal energy content is almost in phase with the amount
of solar radiation (Tabor, 1962). In hot and humid climates, such as in East Asia
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