Optimisation of the filter housing dimensions of an automatic flushing strainer-type filter

Filtration is essential in drip irrigation systems to remove physical contaminants carried by water that can clog the emitters, cause wear, or foul components of the system, affecting its performance and lifespan. Automatic flushing strainer-type filters initiate and terminate discrete flushing cycles that are activated automatically by means of differential pressure. The objective of this study is to investigate the hydraulic performance and flow behaviour of an automatic flushing strainer-type filter operated with clean water, using experimental and numerical approaches, to optimise the dimensions of its filter housing and to increase the range of operating flow rates. Pressure drop curves were determined for the filter housing and the filter system equipped with five models of filter elements (woven and non-woven elements). Excessive pressure drop in the filter housing and low filtration rates were identified as the main drawbacks of the original filter system. Numerical simulations enabled the identification of the most critical regions in terms of pressure losses near the transitions between the inlet and outlet segments of the pipe. Four designs of filter housing were simulated to evaluate the possibilities of optimising the filter housing dimensions using a constant filtering area. Larger inlet and outlet diameters combined to a filter housing shorter and wider were improvements in the filter housing dimensions that enabled to decrease the pressure drop in the filter and/or increase the range of operating flow rates. The results provided useful information for enhancing the hydraulic performance of the filtration system