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龙怀玉,张怀志,岳现录,张认连.负压灌溉重液式负压阀设计与试验[J].农业工程学报,2018,34(1):85-92.DOI:10.11975/j.issn.1002-6819.2018.01.12
负压灌溉重液式负压阀设计与试验
投稿时间:2017-05-16  修订日期:2017-12-10
中文关键词:  灌溉  设计  农业  重液式负压阀,负压灌溉,负压维持
基金项目:国家高技术研究发展计划(863计划)(2013AA102901)
作者单位
龙怀玉 中国农业科学院农业资源与农业区划研究所北京 100081 
张怀志 中国农业科学院农业资源与农业区划研究所北京 100081 
岳现录 中国农业科学院农业资源与农业区划研究所北京 100081 
张认连 中国农业科学院农业资源与农业区划研究所北京 100081 
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中文摘要:为发展负压灌溉中简单实用、高效精确的负压维持方法及其设备,该文设计了一种重液式负压阀(heavy liquid-type negative pressure valve, HLNPV),基本构件包括一个U型玻璃管、一个S型玻璃控压管、一个空心玻璃球以及能在这三者之间进行循环流动的重液-水银,利用水银的静压力维持负压,并且在负压阀和大气之间设计了一个进气速度限制器,利用石蜡油或水覆盖在水银液面上防止其挥发。实验室检测结果表明,在?30 kPa以内的负压下,HLNPV维持负压的相对误差小于5%。实际田间条件下,以石蜡油作为覆盖液时,大部分HLNPV能够在2~3个月的试验期间内平稳运行,有15.5%的HLNPV在运行了1~3个月后发生水银氧化变黑现象,6.2%的HLNPV因为黑色氧化沉淀物堵塞管道而导致负压维持功能丧失。所有以水作覆盖液的HLNPV在2~4个月的试验期间内均能够平稳运行。该文详细地介绍了重液式负压阀的原理、结构、实际使用效果以及进一步改进的建议,以期为促进负压灌溉设备创新研发提供参考。
Long Huaiyu,Zhang Huaizhi,Yue Xianlu,Zhang Renlian.Design and experiment of heavy liquid-type negative pressure valve used for negative pressure irrigation[J].Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE),2018,34(1):85-92.DOI:10.11975/j.issn.1002-6819.2018.01.12
Design and experiment of heavy liquid-type negative pressure valve used for negative pressure irrigation
Author NameAffiliation
Long Huaiyu Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China 
Zhang Huaizhi Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China 
Yue Xianlu Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China 
Zhang Renlian Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China 
Key words:irrigation  design  agriculture  heavy liquid-type negative valve  negative pressure irrigation  negative pressure maintaining
Abstract: Negative pressure irrigation (NPI) is a high efficient irrigation technology which has attracted great concern from some Chinese scholars in the past decade. To produce and maintain a steady negative pressure is an essential key point for NPI, and at present there are mainly 5 methods, namely hanging water column (HWC), static water column (SWC), climbing water column (CWC), electromagnetic valve (EMV) and negative pressure water circulation (NPWC). However, due to some inherent shortcomings, those methods are not convenient to practically operate. The HWC is easily to fail due to the air embolus, the EMV and NPWC are energy-consuming, and too large heights of HWC, SWC, CWC and NPWC make them very cumbersome and not easy to install. In fact, the negative pressure results in the soil water sopping, which is always continuous, slow and unidirectional, and the function of the negative pressure maintaining device is similar to negative pressure limiting valve which does not need to act continuously or high frequently. Therefore, the heavy liquid static pressure should be theoretically used to control the negative pressure in the NPI system. It is known that 1 mmHg which can be easily determined with naked eyes can generate 0.133 kPa static pressure. Moreover, the negative pressure in actual NPI is seldom set under -30 kPa which is equivalent to 22.5 mmHg. Obviously, the negative pressure maintaining device using the static pressure of mercy whose density is the largest in the world to control the negative pressure in NPI should have high precision and small size, and be easily to operate. Accordingly, a heavy liquid-type negative pressure valve (HLNPV) was designed. The HLNPV consists of 3 basic interconnected parts, i.e., a U-shaped tube, an S-shaped pressure maintaining tube and a hollow ball, together with a certain amount of mercury which can be poured into them and cyclically flow in them. The negative pressure is maintained by the static pressure of the mercury in the S-shaped tube. Additionally, a device to slow down the air entering was installed between HLNPV and atmosphere, and the mercury in the hollow ball was overlapped by paraffin oil or water to prevent the evaporation of mercury. Laboratory test showed that the precision of HLNPV could reach 0.1 kPa, which is too enough for NPI, and the relative error of HLNPV with the theoretical control pressure from -5 to -30 kPa was less than 5%, which is satisfactory for NPI. In the field, most paraffin oil overlapping HLNPV could steadily run for the whole experiment period of 2-3 months, while the mercury in 15.5% of the HLNPV was oxidized after running for 1-3 months, and that in 6.2% of the HLNPV was blocked up by the oxide precipitate, which caused their failure to maintain negative pressure. Water-overlapping HLNPV could steadily run for the whole experiment period of 2-4 months, while water is a theoretic volatile liquid, if the runtime is more than 4 months, the overlapping water maybe need to be complemented. In one word, the HLNPV can overcome many disadvantages of the present negative pressure maintaining methods, and has the advantages of larger negative pressure, no energy consumption, small size, high accuracy, easy to install and debug, as well as more security. The mechanism, structure, application effect and suggestions for improvement of the HLNPV are described explicitly in this paper, thereby providing a reference for its further application, innovation and improvement.
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