Optimization of structural parameter for disc filter in drip irrigation system

Disc filter has been widely applied in irrigation field, due to its better backwashing. However, the head loss of disc filter can sharply increase to the critical range in a short time. It is still lacking on the reasonable and scientific configuration of disc filter products, according to the different irrigation water and the emitter types. In addition, the existing products of disc filter cannot fully meet the requirements under the various irrigation water in drip irrigation. Even filtering has been abandoned in practical applications. As a result, the disc filters are seriously restricted. It is very necessary to select the suitable products of disc filter with the various structural parameters. This study aims to avoid the steep increase of the head loss for the high efficiency of filtering. Multiple disc filters were designed by adjusting the aperture between adjacent laminations. The optimal accuracy of filtering was obtained under the critical number of laminations. The hydraulic and filtering performance of the disc filter were evaluated under the sandy water with five grading levels of sand particle size. A systematic investigation was made to determine the growth rate of head loss in the clogging periods, the clogging uniformity of disc filters, and the discharge deviation rate of emitters under different operating conditions. A multi-objective evaluation model was constructed using fuzzy comprehensive evaluation (FCE), considering the different irrigation sandy water, disc filters and micro irrigation emitters. The results show that the disc filters with adjustable aperture between adjacent laminations were achieved in the filtering sand with the large ranges of sand particle size. Disc filter with five apertures intercept sand particle sizes were 49, 82, 100, 127, and 150 μm. The above mentioned particle size refered to the median particle size of the minimum particle size grading in the sand segment with an interception rate greater than 90%. The particle size was smaller in the sandy water, as the aperture of disc filter decreased, indicating the more significant increase in the head loss. There was the consistence between the comprehensive evaluation results and experimental performances of disc filter under the different irrigation sandy water and the emitter types. The comprehensive evaluation indexes were sorted to select the irrigation sandy water, the aperture of disc filter and the emitter type. The slight clogging was simultaneously obtained for the emitter and stable performance of disc filter under efficient operation in the entire irrigation system. The optimal structural parameters of disc filters can provide a strong reference for the rational configuration of disc filters. The finding can also offer new optimization design ideas for the adaptability of disc filters.