三七土壤水蒸气消毒针结构设计与试验

Structural Design and Test of Soil Steam Disinfection Needle in Panax notoginseng Field

针对连作障碍严重制约三七种植可持续发展的问题,设计一种针式水蒸气输出装置,对消毒针的结构参数进行优化,并通过土槽试验进行验证。通过Fluent软件对消毒针内部进行仿真,结果表明,消毒针出口流速、压力增大,出口温度无明显变化。土壤热传导试验表明,在5 min内即可将土壤加热到90℃,土壤加热基本规律为下层土壤加热效率较低、上层土壤加热效率高。为了探究消毒针不同结构参数对土壤升温效果的影响,选取单侧孔口数量、孔口直径和水蒸气出射角作为试验因素,选取土壤升温到90℃所需时间作为试验指标,进行了正交试验,确定消毒针最优结构参数组合为:消毒针单侧孔口数量为4个、孔口直径为2 mm、水蒸气出射角为45°,此时土壤升温到90℃时间最短,为116 s。通过Fluent多孔介质传热仿真得出,消毒针的最佳排布方式为6×6,最佳数量为36根,间距为250 mm。对消毒后的土壤有机质含量及pH值进行检测,表明消毒后土壤环境符合三七生长的环境要求。

Aiming at the problem of continuous cropping obstacles that seriously restrict the sustainable development of Panax notoginseng planting,a needle steam output device was designed.The structural parameters of the disinfection needle were optimized and verified by the soil-bin test.The simulation experiments of the needle’s internal were carried out by Fluent software,the test results showed that the flow rate and pressure of the disinfection needle were increased,and no significant change in outlet temperature was found.The basic law of soil heating was verified by the soil-bin test.The soil can be heated to 90℃in 5 minutes,and the heating efficiency of the lower soil was low,and that of the upper soil was high.In order to explore the effect of different structural parameters of the disinfecting needle on the warming effect of the soil,the number,diameter and steam emission angle of the hole on one side were selected as the test factors of the soil-bin test,and the time required for the soil to rise to 90℃was selected as the test index,and orthogonal tests were carried out respectively to determine the optimal structural parameters of the disinfecting needle.When the number of single side orifices was 4,the diameter of the orifice was 2 mm,and the steam exit angle was 45°,the heating time of soil by the disinfection needle structure was the shortest,for 116 s.The optimal arrangement of disinfection needles was 6×6 layout,the optimal number was 36,and the spacing was 250 mm by the heat transfer simulation of Fluent porous media.The changes in soil organic matter and pH value after disinfection were tested,the soil environment after disinfection met the environmental requirements for the growth of Panax notoginseng.