2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 218 -
T. Chanprasopchai, W. Saman and E. Halawa
Institute for Sustainable Systems and Technologies, School of Advanced Manufacturing and Mechanical Engineering,
University of South Australia,
(Australia)
Abstract
--
The experimental performance of a low flow
rate plate regenerator of a solar liquid desiccant cooling/
dehumidification system is presented. The study investigates
the effects of flow rates and temperatures of water, air and
desiccant solution on the regenerating capacity in term of
change in the solution concentration. In the experiments, the
air humidity and temperature were set to represent the
design conditions of Bangkok, Thailand. The desiccant flow
rates were set within a range with the maximum value of
0.014 l.s
-1
. Air flow rates were varied in the range 0.213-
0.364 kg.s
-1
. The water flow rates were maintained within
the range 200 and 300 kg.hr
-1
while the temperatures were
kept at 50-83
○
C range. The results show that air flow rate
has insignificant effect on concentration change whilst the
water flow rate and temperature increase concentration
change. On the other hand, the solution flow rate decreases
the concentration change.
Index Term
--alternative cooling, liquid desiccant,
regenerator, solar cooling
I. N
OMENCLATURE AND
S
UBSCRIPTS
Nomenclature
m
a
air flow rate at the regenerator, kg.s
-1
m
s
desiccant solution mass flow rate, kg.s
-1
m
w
water flow rate, kg.s
-1
V
s
desiccant solution volume flow rate, l.s
-1
W
air humidity ratio, kg.kg
-1
x
solution concentration, kg.kg
-1
Subscripts
a air
db dry bulb temperature
in inlet
out outlet
s desiccant solution
w water
wb wet bulb temperature
II. I
NTRODUCTION
The liquid desiccant system is a thermally driven
dehumidification/cooling system which is potentially a
viable alternative to traditional cooling systems. As this
system can be driven by low temperature thermal energy
such as low grade solar or waste energy, it can reduce
peak electrical demand, power consumption and
greenhouse gas emission.
A number of studies have been carried out on different
types of regenerators, such as solar collector/regenerator
[1-3], plate type [4-6] and packed bed type [7-9]. Liu
[10], who studied hot air driven and hot desiccant driven
regenerators, states that the desiccant solution should be
heated as a first priority then air as a consequence.
However, he explains that a hot air driven regenerator has
better mass transfer in parallel flow while hot desiccant
regenerator is better in counter flow. Saman et al. [11]
and Ren et al. [12] studied a hot water driven regenerator.
Yin et al. [13] indicated that the regeneration efficiency
of an internally-heated regenerator is higher than the
adiabatic regenerator.
This paper reports on an experimental investigation on
the performance of an internally heated water plate
regenerator of a low flow solar liquid desiccant
cooling/dehumidification system. This arrangement has
been demonstrated to eliminate potential issues
associated with liquid desiccant carry over [14].
III. M
ETHODOLOGY
A. System Description
Fig. 1 shows a schematic diagram of the solar liquid
desiccant cooling system. There are two main
components, namely the absorber and the regenerator.
The absorber dehumidifies the process air and releases
the moisture to the desiccant solution which becomes
weak. The air then passes through a cooling device such
as an evaporative cooler before it is supplied to the
conditioned room.
Fig. 1.
Schematic diagram of a liquid desiccant cooling system.
After absorbing the moisture in the absorber, the weak
desiccant solution needs to be regenerated. Fig.2 shows a
schematic diagram of a regenerator. The device consists
of flat plate containing internal channels assembled in
Experimental Performance of a Low Flow Rate
Regenerator of a Solar Liquid Desiccant
Cooling/Dehumidification System
