Abstract:
Abstract: From the 1980s, China had begun to introduce water-saving irrigation technology and equipment, but China's water-saving equipment research and development mainly relied on technology introduction and product imitation and did not have a completely independent design method and innovative products. Drip irrigation is the most common water-saving irrigation technology. The emitter and the filter are the 2 core devices of the drip irrigation project. The filter with excellent performance can make the water entering the pipe network system qualified, prevent the emitter from being blocked, and ensure the normality of the drip irrigation system when running. A good emitter can make the irrigation water drip into the irrigation area evenly, and has the high anti-blocking ability. The pressure-compensating emitters can achieve stable flow in a wide range of working water pressure changes, so its application range is wider. At present, the pressure-compensating emitters used in the market are imported products from abroad. The production process of these products is complex, requiring multiple molds, high production costs, long cycles, and difficult product quality control. In the promotion of drip irrigation technology, the recovery of drip irrigation belts or emitters is a bottleneck that needs to be overcome in the promotion of drip irrigation technology in China. To overcome the “difficulty of recycling” of pressure-compensating emitters of silicone tablets, this paper designed and developed an all-plastic-integrated pressure-compensating emitter containing thermoplastic elastomer (TPE). TPE is a new type of polymer material that exhibits rubber-like elasticity at normal temperature and can be plasticized at high temperature. Because of its rubber elasticity and easy processing of plastics, TPE has been widely used in various fields. The design emitter was made of TPE and low-density polyethylene materials. Based on the principle of pressure-compensating emitter flow compensation and numerical calculation method of computational fluid dynamics with Ansys 15.0, this study used an orthogonal design test on some important factors of the emitter, such as tip angle, channel width, channel depth, number of channel quantity. With the optimized design which parameter combination tip angle 34°, channel width 0.4 mm, channel depth 0.4 mm, number of channel quantity 12, the emitter was manufactured and tested for its compensating performance and anti-clogging performance. The results showed that the integral pressure-compensating emitter had a flow index of 0.07, a starting compensation pressure of 35 kPa, and a compensation range of 35-300 kPa. With well compensation performance, it belonged to the regulated pressure-compensating emitter; compared with one domestic emitter, the hydraulic performance of the integral pressure-compensating was much better; under low-pressure conditions, the integral pressure-compensating emitter had better anti-clogging performance than the B and C emitters. For example, when the sediment concentration was 1.0 g/L and the system pressure was 50 kPa, and 15 times irrigation later, the relative flows of the emitter A, B and C dropped to 93.1%, 54.2%, and 81.8%, respectively. Based on the integrated "all-plastic" design, the integral pressure-compensating emitter used a two-color injection on rapid prototyping which injected the mold of LDPE followed TPE material, and the two materials could be quickly combined. It was 15%-35% of the production cost of the traditional three-piece (substrate, silicon sheet, base) structure pressure-compensated emitter, and the production efficiency was increased by 50%-150%. Low production cost, short development cycle and easy recycling, it is a better substitute for the traditional emitter, and the study results provide valuable information for the integrated pressure-compensating emitter on construction designing and developing.