2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 223 -
The moisture gain is still higher than moisture loss at
around 0.16 g.s
-1
for water flow rate at 200 kg.hr
-1
(see
Fig. 13a), and 0.5 g.s
-1
for water flow rate at 300 kg.hr
-1
(see Fig. 13b).
a.
b.
Fig. 13. Effect of air flow rate on moisture gain in the air and moisture
loss in solution a. water flow rate at 200 kg.hr
-1
b. water flow rate at 300
kg.hr
-1
(Conditions: V
s
= 0.01 l.s
-1
, T
w
= 80
○
C, T
wb
= 28
○
C, T
db
= 36
○
C).
The moisture gain in the air is generally higher than
the moisture loss from solution at average about 0.2 g.s
-1
.
The maximum moisture gain is around 1.8 g.s
-1
and
maximum moisture loss is approximate 1.7 g.s
-1
.
C. Comparison with Previous Results
A number of previous investigations express the
regenerator performance in terms of moisture increase in
the air [16, 17]. The current work however expresses the
performance in term of the change of solution
concentration in the regenerator. This is due to the fact
that in the absorber, it is the concentration of solution
which dictates the effectiveness of moisture transfer from
the air to be humidified to the solution.
A number of investigations have been carried out to
study the performance of the regenerators. Fumo and
Goswami [18] studied the air dehumidification and
desiccant regeneration using packed tower absorber and
regenerator. Katejanekarn and Kumar [19] studied the
performance of solar-regenerated liquid desiccant
ventilation pre-conditioning system. They used the solar
collector/regenerator (C/R) to regenerate the desiccant
solution.
TABLE
I compares the parameters in three different
investigations on regenerators employing Lithium
Chloride (LiCl) as the solution. Three different types of
regenerators are used; C/R, pack and plate regenerator
with different surface area. The experimental conditions
such as desiccant flow rate and temperature, and air flow
rate are all different. This makes it difficult to compare
the results of the current investigation with those
mentioned earlier.
TABLE
I
C
OMPARISON
P
ARAMETERS ON THE
R
EGENERATOR
Given this, in Table II, only trends of the evaporation
rate affected by individual parameter are shown.
TABLE
II
C
OMPARISON OF
T
HE
E
FFECT OF
V
ARIOUS
P
ARAMETERS ON THE
T
REND
OF
E
VAPORATION
R
ATE
Parameters
Evaporation rate
Present
study
Fumo and
Goswami [18]
Katejanekarn
and Kumar [19]
Desiccant solution
flow rate
↑
↑
↓
Air temperature
↑
→
↑
Air flow rate
→
↑
→
x
↑,↓,→ are increase, decrease and little or no change, respectively
The effect of desiccant flow rate on evaporation rate in
Fumo and Goswami [18] and in the present study is
similar, i.e. it increases the evaporation rate. This is
opposed to
Katejanekarn and Kumar’s experiments [19]
where the desiccant flow rate decreases the evaporation
rate. It must be noted that these three studies have
different rates of evaporation, i.e. 1.7-1.9 g.s
-1
for Fumo
and Goswami, 0.3-1.1 g.s
-1
for the present study and less
than 0.1 g.s
-1
for Katejanekarn and Kumar.
The effect of air temperatures are similar for
Katejanekarn and Kumar’ [19] and the present study, i.e.
it increases the evaporation rate. This is opposed to Fumo
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.20
0.25
0.30
0.35
0.40
Moistureremoval rate
g.s
-1
Air flow rate kg.s
-1
Moisture gain
Moisture loss
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.20
0.25
0.30
0.35
0.40
Moistureremoval rate
g.s
-1
Air flow rate kg.s
-1
Moisturegain
Moisture loss
Parameters
Present study
Fumo and
Goswami [18]
Katejanekarn
and Kumar [19]
Regenerator
Internally
heat plate
regenerator
Pack
regenerator
Solar collector/
regenerator
Surface area
15.4 m
2
5.7 m
2
5.85 m
2
Desiccant
solution
LiCl
LiCl
LiCl
Desiccant
flow rate
9.5-47.9 l.hr
-1
5.18-7.54
kg.s
-1
.m
-2
30-120 l.hr
-1
Desiccant
temperature
Ambient
(15.9-26.2
○
C)
60.3-70.0
○
C
25.0-28.8
○
C
Concentration
0.276-0.330
kg.kg
-1
0.328-0.349
kg.kg
-1
0.30-0.45
kg.kg
-1
Air
temperature
Dry bulb
31.7-50.8
○
C
29.4-40.0
○
C
26.0-39.6
○
C
Wet bulb
19.9-29.2
○
C
Not reported
Not reported
Air flow rate
0.014-0.024
kg.s
-1
.m
-2
or
0.212-0.364
kg.s
-1
0.833-1.438
kg.s
-1
.m
-2
0.02-0.20 kg.s
-1
Air humidity
0.007-0.023
kg.kg
-1
0.0143-0.021
kg.kg
-1
0.0134-0.0221
kg.kg
-1
Hot water
flow rate
100-400
kg.hr
-1
Not used
Not used
Hot water
temperature
50.2-82.8
○
C
Not used
Not used
