Monthly Archives: July 2016

 Q: What is Cross Flow Velocity?  

A: Cross flow velocity (CFV) is the linear velocity of the flow tangential to the membrane surface and is reported in [m/sec] or [ft/sec]. CFV affects the hydrodynamic conditions in the cell, and as a result affects the fouling rate and formation of concentration polarization at membrane surface and is calculated by dividing the volumetric flow rate [lpm or gpm] in the flow channel by the cross sectional area [m² or ft²] of the flow channel.  

Q: How is CFV calculated in Sterlitech’s bench-scale test cells?  

A: Example: Calculate CFV in the CF042 cell  

• Flow channel cross sectional area: Channel depth x Channel width* = 0.23 x 3.92 cm

Sterlitech teamed up with Senior Engineering Students at California State Polytechnic University, Pomona (Cal Poly Pomona) to evaluate the design of a tangential flow Air Gap Membrane Distillation (AGMD) test cell. Membrane Distillation (MD) is a thermally driven membrane separation technique used for desalination. In this process, the driving force is the difference in the vapor pressure on both sides of the membrane, where permeate travels through a hydrophobic membrane in a vapor phase. Advantages of MD process over conventional distillation or pressure driven separation processes are:

• Low Operating Pressures
• Low Operating Temperatures
• Less Susceptibility to Fouling

These all translate to lower energy requirements that make MD an energy efficient separation process. Scope of the Project: A bench-scale tangential flow test cell is configured in this project where feed solution is circulated tangentially

Water, oils, and solvents sometimes need to be filtered. But when you see filters labeled as hydrophilic, hydrophobic, and now oleophobic; what does all this mean?  Sterlitech currently offers membrane disc and sheet filters in 10 different polymer types and 4 inorganic filters. 2 of the polymer types are subdivided into 4 subgroups based on surface chemistry alone.

Filters listed as hydrophilic, which has its origins in the Greek language and means water (hydro) loving (philos), love to get wet! Hydrophilic filters will easily pass water or water-based solutions such as dairy, river water, seawater, cell culture solutions, buffers, beverages, and many more. The filters best suited to handle these solutions are silver, ceramic