Membrane and Desalination Technologies - TCE Moodle Website

Adsorption Desalination: A Novel Method 417
4. For the evaporator
and
Q latent
cond ¼ msilica gel
dq bed
des
dt hfg: (20Þ
Qchill ¼ _mcp chill Tchill;in Tchill;o ; (21Þ
Q latent
evap ¼ msilica gel
dq bed
ads
dt hfg: (22Þ
The sensible and latent heat balances of the adsorption cooling system are
Qads þ Qcond ¼ Qdes þ Qchill
Q latent
ads
þ Qlatent
cond
¼ Qlatent
des
(23Þ
þ Qlatent evap ; (24Þ
respectively.
In the above-mentioned equations, _mdes, _mcooling, _mchilled, and _mcond are the mass flow rates
of hot water, adsorber cooling water, chilled water, and condenser cooling water, respectively.
T hw,in, T cw,in, and T chll,in stand for a hot, cooling, and chilled water inlet temperatures.
Thw,o, Tcw,o, and Tchll,o are hot, cooling, and chilled water outlet temperatures, respectively.
As AD is aimed to produce potable water, the end user may be more concerned with the
specific daily water production and the system performance ratio. In this context, the SDWP
and PR are, respectively, defined as given in the following relations:
ð
3; 600 dQcond
SDWP ¼
t dt; (25Þ
hfg ðTcond Þ msilica gel
where t is the number of running hours of the plant. For more accurate and realistic results,
Qcond is used to evaluate SDWP. However, in real calculation of the water production, the
readings from the flow meter are used as follows:
SDWP ¼
1; 440
N
P N
i¼1
ðFÞi ; (26Þ
where F is condensate water flow rate measured in LPM and msg is the mass of silica gel used.
The performance ratio of the adsorption desalination process is expressed as
PR ¼
msg
ð _mwaterh fgðTcondÞ
dQdes
dt; (27Þ
where dQcond is the heat rejected at condenser and dQdes is the heat of desorption during the
desorption process.