This thesis focused on the development of a new separation technology to separate or fractionate particles from aqueous suspensions. The separation principle is discovered in physical studies to geometric interactions between suspended solids and obstacle patterns in microfluidic channels.
Depending on the particle size and the design of the obstacle pattern it appeared that obstacles may displace particles in another direction than the main flow direction. It is a main advantage that the distance between obstacles is several times larger than the particle size. This minimizes the risk for obstruction and it results in a very low pressure drop over the system. Therefore, the principle is highly interesting for application in the process industry.
Suspension separation at a lager scale
Because microfluidic systems have a very limited capacity, this research was directed to understanding of the mechanisms relevant for suspension separation at a larger-scale. With a newly developed up-scaled experimental set-up was discovered that the separation efficiency increases with increasing flow rates.
Using high speed camera techniques and numerical simulations is has been stated that this dependency on flow rate was caused by inertia and local fluid instabilities. Furthermore, mirrored obstacle patterns were investigated for more efficient particle separation or fractionation. Finally, a new obstacle pattern with minimal pressure drop has been designed. This design can be up-scaled rather easily and is also suitable for the separation of smaller particles.