摘 要

针对设施农业高密度栽培及同一地块上连年种植作物 ,使得土传病害、病原菌得以不断的积累、生长和繁殖而造成严重减产或降低产品质量的问题，阐述了栽培土壤消毒的必要性，简要地说明了土壤蒸汽消毒的基本方法和原理。本课题需要试验研究蒸汽在土壤中传热的传热特性，研究出影响土壤传热效果的因素，为土壤蒸汽消毒机输送装置的结构设计提供理论和实验基础。试验结果表明单针头试验时单针头的热作用半径为8-10cm，热作用深度为1-21cm。多针头试验时，蒸汽注射时间需要设定为5min即可满足消毒要求；理想的蒸汽压力为0.4Mpa；土壤含水率越高，土壤的传热性能就越好。蒸汽输送装置的结构设计，包括采用液压系统来控制蒸汽盘的运动，使之能够收放自如；蒸汽盘四周的罩壳的设计保证与土壤接触部分具有较好的密封性；针头不同深度的周向小孔的设计保证了蒸汽在土壤中分布均匀，起到良好的消毒效果。

本课题先通过搭建实验室土壤蒸汽消毒测试系统，研究蒸汽压力、注射时间、注射深度、针头结构和管路布置等对土壤传热效果的影响，然后对蒸汽输送装置进行结构优化设计，从而保证良好的土壤蒸汽消毒效果。

关键词：土壤；消毒；蒸汽输送装置；土壤传热特性

Structural Design of Steam Conveying Device for Soil Steam Sterilizer and Experimental Study on Heat Transfer Characteristics of Steam in Soil

ABSTRACT

Given the fact that in installment agriculture,highly-density and successive plantation on the same soil cause the accumulation ,growth ,reproduction of soil-bome diseases and pathogeny,which in turn cause severe reduction in quantity and quality of product.This article elaborated the necessity of cultivation soil’ s sterilization,and briefly explained the essential method and principle soil steam sterilizer. The subject needs to study the heat transfer characteristics of steam in the soil, and study the factors that affect the heat transfer effect of the soil, and provide the theoretical and experimental basis for the structural design of the conveyor device of soil steam sterilizer.The results show that the single needle has a thermal action radius of 8-10 cm and a thermal depth of 1-21 cm. In the multi-needle test, the steam injection time needs to be set to 5min to meet the disinfection requirements; the ideal steam pressure is 0.4Mpa; the higher the soil moisture content, the better the heat transfer performance of the soil. The structural design of the steam conveyor includes the use of a hydraulic system to control the movement of the steam disc so that it can be freely discharged. The design of the enclosure around the steam tray ensures a good seal with the soil contact; The design of the hole to ensures that the distribution of steam in the soil evenly, plays a good disinfection effect.

In this paper, the soil steam sterilization test system was used to study the effects of steam pressure, injection time, injection depth, needle structure and pipe arrangement,and then optimize the design of the structure of steam conveying device, so as to ensure a good soil steam disinfection effect.

Key words: soil; sterilization;steam conveyor;heat transfer characteristics of steam in the soil

目 录

第一章 绪论..................................................................01

1.1 研究背景、目的及意义.....................................................01

1.2 国内外研究概况...........................................................01

1.2.1 目前国内外土壤消毒机蒸汽输送方式......................................02

1.2.2 土壤消毒机蒸汽传输方式国外研究概况....................................03

1.2.3 土壤消毒机蒸汽传输方式国外研究概况....................................04

1.3 土壤蒸汽消毒机的工作原理.................................................05

1.3.1 土壤蒸汽消毒机的工作原理概述..........................................05

1.3.2 脉动燃烧知识的介绍....................................................05

1.4 蒸汽消毒法的优缺点.......................................................06

1.5 本章小结.................................................................07

第二章 蒸汽在土壤中传热特性试验研究..........................................08

2.1 蒸汽传热的机理和土壤热迁移机制...........................................08

2.1.1 蒸汽传热的机理........................................................08

2.1.2 土壤热迁移机制........................................................09

2.2 土壤蒸汽传热特性测试系统介绍.............................................10

2.2.1 试验用蒸汽发生装置....................................................11

2.2.2 试验用蒸汽输送装置....................................................12

2.2.3 测温装置..............................................................14

2.2.4 试验用土壤............................................................15

2.3 单针头注射传热试验.......................................................16

2.3.1 试验目的和内容........................................................16

2.3.2 蒸汽温度损失..........................................................16

2.3.3 单针头注射时间因素分析................................................17

2.3.4 蒸汽压力因素分析......................................................18

2.3.5 单针头热作用横向半径分析..............................................19

2.3.6 单针头热作用纵向深度分析..............................................20

2.4 多针头注射传热试验.......................................................21