Study On The Performance Of Semi-permeable Membrane Moistube

With the development of the materials science, a new type of water-saving irrigation equipment been made, called the Semi-permeable membrane Moistube. Based on the soil water potential difference and unidirectional permeability of semi-permeable membrane, it can achieve regulating the crop water requirement timely. Semi-permeable membrane Moistube is a new type of water-saving irrigation equipment which referred to the technique of semi-permeable film water-saving irrigation, the crop full life cycle of continuous irrigation is achived by using soil water potential difference and unidirectional permeability of semi-permeable film, and it can achieve regulating of Crop water requirement timely. So this research is significant to water-saving technology. The flow law, infiltration characteristics, anti-clogging performance, and hydraulic calculation of the Moistube are studied in this paper, and achived some initial results.In the outflow experiment, Results shown that the flow and pressure of the moistube have a significant linear relationship, under a constant water head, the flow is constant, when the water head changing, the flow will have a liner variation. In addition, the flow of the 1#moistube is about three-four times of the 2#, according the water requirement in plants to select the suitable model. The objective of this study was to investigate the influence of tiny sediment particle in muddy water on anti-clogging performance of the semi-permeable membrane moistube. A serious of muddy water with different particle size distribution, sediment concentration, water head and pipe length were tested by the continuous irrigation method. Based on the experiments, the effect of the three factors for the clogging of the moistube was analyzed. Meanwhile, the range of the sensitive particle diameters and the level of sediment concentration were discussed. The results shown the positive relationship between sediment concentration and the clogging progress. Moreover, the moistubes are prone to being clogged when particle size between 0.061 and 0.1mm, under the same water conditions, the clogging degree of the mositube will reduce. The pipe length had significant effect on the clogging and the high pressure water for the flushing of the pipe had a good result.In the infiltration experiment, it analyzed the effect of different water head to the wetting front through indoor soil box experiment,established the formula for predicting the volume of the wetted soil. The results shown during infiltration process, the wetting front appears as round; pressure head have a significant impact on the wetting front, with the increased water head the advancing rate of the radius speeding up, and the wetting front between the irrigation time have a power function relationship. Soil moisture content was symmetrical centered on moistube, the farther the distance from the Moistube the lower for the moisture content. According to micro-irrigation hydraulics characteristic, combining the search principle of bi-section algorithms and back step method, Simulation results suggest that the method has a great solution efficiency, computational accuracy and reliability. In addition, the hydraulic calculation and the experiments of the moistube shown that the head loss is very small and the irrigation uniformity is high.