Module Operating Conditions Research Articles

Membrane gas transfer under conditions of creeping flow: modeling gas composition effects

A computational model was developed to predict gas transfer and gas composition changes in membrane modules designed for addition of gases to groundwater. The model was verified using pilot-scale gas transfer experiments. The modeling and experimental results suggest that back diffusion of dissolved gases into the membrane has a significant effect on gas transfer via hollow-fiber membrane. In the experimental study, N2 back-diffusion reduced the partial pressure of O2 within the membrane and decreased the concentration gradient for gas transfer. The model was able to simulate both the dynamic and steady-state gas transfer behavior of the membranes under a variety of operating conditions. This model can be used to estimate gas transfer as a function of different membrane module design and operating conditions.

Membrane gas transfer under conditions of creeping flow: modeling gas composition effects

A computational model was developed to predict gas transfer and gas composition changes in membrane modules designed for addition of gases to groundwater. The model was verified using pilot-scale gas transfer experiments. The modeling and experimental results suggest that back diffusion of dissolved gases into the membrane has a significant effect on gas transfer via hollow-fiber membrane. In the experimental study, N 2 back-diffusion reduced the partial pressure of O 2 within the membrane and decreased the concentration gradient for gas transfer. The model was able to simulate both the dynamic and steady-state gas transfer behavior of the membranes under a variety of operating conditions. This model can be used to estimate gas transfer as a function of different membrane module design and operating conditions.

Theoretical optimization of spiral-wound and capillary nanofiltration modules

The performance of spiral-wound (SPW) and capillary nanofiltration (NF) modules can be improved by optimizing the module configuration and operating conditions. To this effect, two mathematical models for spiral wound and capillary modules have been developed. Both models are based on the homogeneous solution model and take into account concentration polarization, difference in rejection of mono- and bivalent ions, and the pressure drop in the feed and permeate channel. In this paper the influence of the operating conditions (feed pressure, feed flow) and the module configuration (spiral wound, capillary, feed channel height, permeate channel height, porosity, capillary diameter) on the performance of the modules are presented. Compared to the optimized spiral-wound module, a further increase in performance of 100% can be achieved by optimizing the configuration and operation conditions of a capillary module.