Frontiers of Chemical Science and Engineering >
CFD simulation on membrane distillation of NaCl solution
Received date: 17 Sep 2008
Accepted date: 22 Jan 2009
Published date: 05 Sep 2009
Copyright
A computational fluid dynamics (CFD) simulation that coupled an established heat and mass transfer model was carried out for the air-gap membrane distillation (AGMD) of NaCl solution to predict mass and heat behaviors of the process. The effects of temperature and flowrate on fluxes were first simulated and compared with available experimental data to verify the approach. The profiles of temperature, temperature polarization factor, and mass flux adjacent to the tubular carbon membrane surface were then examined under different feed Reynolds number in the computational domain. Results show that the temperature polarization phenomena can be reduced, and mass flux can be enhanced with increase in the feed Reynolds number.
Zhaoguang XU , Yanqiu PAN , Yalan YU . CFD simulation on membrane distillation of NaCl solution[J]. Frontiers of Chemical Science and Engineering, 2009 , 3(3) : 293 -297 . DOI: 10.1007/s11705-009-0204-7
D | inner diameter of the tubular carbon membrane |
Hv | latent heat of evaporation |
h1 | the condensation heat transfer coefficient |
hc | heat transfer coefficient at cooling plate |
J | mass flux |
k | thermal conductivity |
L | length of the tubular carbon membrane |
Mw | molecular weight of water |
N | molar flux |
Pavg | average totoal pressure |
pfm | partial pressure of water on the feed side |
pmg | partial pressure of water on the membrane/air-gap interface |
pv | saturation pressure |
q | heat flux |
qcm | conductive heat flux across the membrane |
qvm | vaporization heat flux across the membrane |
R | universal gas constant |
Re | Reynolds number (Re= ρuD/μ) |
r0 | the average pore radius of the membrane |
Tavg,m | the average temperature of the membrane |
Tf | the feed temperature at the inlet |
Tfm | the feed temperature adjacent to membrane surface |
Ufc | overall heat transfer coefficient |
u | axial velocity |
v | radial velocity |
x | axial coordinate |
xNaCl | molar fraction of the NaCl solution |
y | radial coordinate |
ΔP | pressure difference beteween the membrane |
αw | the activity coefficient of water |
δ | thicknes |
ϵ | porosity |
μ | viscosity |
Θ | temperature polarization factor |
ρ | density |
τ | tortuosity |
a | air |
c | coolant |
fp | condensate film/cooling plate interface |
g | air-gap |
gf | air-gap/condensate film interface |
m | membrane |
mg | membrane/air-gap interface |
p | cooling plate |
pc | cooling plate/coolant interface |
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