Spacer-filled channels

The area required for processing A = Qo — QVJ, where Qo Q is the perrneate volumetric flow, can be estimated by using the approximation / = 0.33/initiai + 0.67/finai (Cheryan, Ultrafiltration Handbook, Technomic, Lancaster, Pa., 1986) and a suitable flux model. An appropriate model relating flux to crossflow, concentration, and pressure is then applied. Pressure profiles along the retentate channel are empirically correlated with flow for spacer-filled channels to obtain A = APfQ/AT. 

A.R. Da Costa, A.G. Fane and D.E. Wiley, Spacer Characterization and Pressure Drop Modeling in Spacer-filled Channels for Ultrafiltration, J. Membr. Sci. 87, 79 (1994). 

Schwinge J., Wiley D.E., and Fletcher D.F., A CFD study of unsteady flow in narrow spacer-filled channels for spiral-wound membrane modules. Desalination 146 2002 195-201. 

Lipnizki J. and Jonsson G., Flow dynamics and concentration polarization in spacer-filled channels. Desalination 146 2002 213-217. 

Concentration and temperature polarization can be reduced by the presence of spacers that are mrbulence promoters, which enhance the mass flux by increasing the film heat transfer coefficient. Spacers also change the flow characteristics and promote regions of turbulence thus improving boundary layer transfer [106]. DCMD in spacer-filled channels have been shown to improve flux by 31% 1% than that without spacers. The temperamre polarization coefficients are substantially increased and approach unity when the spacers are used in the channels. 

Da Costa, A.R. (1993), Fluid flow and mass transfer in spacer-filled channels for ultrafiltration, PhD... 

Neal PR, Li H, Fane AG, Wiley DE. The effect of filament orientation on critical flux and particle deposition in spacer-filled channels. J. Membr. Sci. 2003 214 165-178. 

The unexpected results of Sablani et al. [17] (i.e., less turbulence with smaller spacer thickness) may be best explained by an excellent paper by Schwinge et al. [82], The latter employed computational fluid dynamics (CFD) in a study of unsteady flow in narrow spacer-filled channels for spiral-wound membrane modules. The flow patterns were visualized for different filament configurations incorporating variations in mesh length and filament diameter and for channel Reynolds numbers, Re y, up to 1000. The simulated flow patterns revealed the dependence of the formation of... 

Figure VII - 7. Schematic drawing of a spacer (upper figure) and a spacer filled channel (lower...

The flow conditions in the thin feed brine channel with feed brine spacers in between is complex (see Schwinge et al. (2002, 2003) for the unsteady flow, vortex shedding and mass-transfer enhancement in spacer-filled channels). The complexity is captured by using an empirically... 

The flow becomes highly complex in a spiral-wound module containing a feed-side spacer screen. Numerical solutions of the governing equations incorporating most of these complexities have been/are being implemented (Wiley and Fletcher, 2003) using computational fluid dynamics models (see Schwinge et al. (2003) for the complex flow patterns in a spacer-filled channel). 

Gao Y, Haavisto S, Tang CY, Salmela J, Li W (2013) Characterization of fluid dynamics in spacer-filled channels for membrane filtration using doppler optical coherence tomography. J Membr Sd 448 198... 

The analysis of pressure drop within spacer-filled channels can be found in Da Costa et al Recently a double helix spacer with enhanced mass transfer characteristics combined with a reduced pressure drop was developed at RWTH Aachen University. ... 

Other authors (Martmez-Di ez et al., 1998 Phattaranawik et al., 2001) have considered the use of spacer-filled channels of plate-and-frame membrane modules used in DCMD. It was observed that DCMD permeate fluxes were higher when using a screen separator than when an open separator was used. The spacers changed the flow characteristics and promoted regions of turbulence, leading to a decrease of the temperature polarization. These effects were found to be higher for the coarse spacer than for the fine spacer. 

Phattaranawik, J., Jiraratananon, R., Pane, A. G., and Halim, C. (2001). Mass flux enhancement using spacer filled channels in direct contact membrane distillalion. J. Membr. Sci. 187, 193. 

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