Optimisation of flow through a horizontal spiral baffled filter

This dissertation presents a solution to the phenomena of water channelling in a horizontally orientated sand filter. The aim is to find an optimal configuration of spiral baffle for a particular residence time and power input. A total of nine different spiral baffle geometries were considered. The methodology for optimisation was to use computational fluid dynamics (CFD) software to study the flows in all nine geometries. A multiphase model was used to estimate the residence time of a volume fraction of fluid within the nine geometries. The residence time was then compared to the power input data to derive a solution. Results show so far that by increasing the pitch the power requirement to drive the filter decreases. In addition to this as the baffle height is increased the power requirement increases also. The spiral baffle represents a real solution to the problem of water channelling in a horizontal sand filter. One of the benefits of the spiral baffled filter could be the treatment of ground waters in developing countries. The advantage of the horizontal filter is that it could be made portable. With a portable sand filtration system the production of quality water could be achievable anywhere