【作者】 高亚辉；

【导师】 陈曦；

【作者基本信息】 河南工业大学 ， 土木工程， 2024， 硕士

【摘要】 粮食自古就担任着人类存续与社会进步的核心角色,粮食安全问题事关世界和平与发展以及人类命运共同体的构建。近年来,地下粮仓低温储粮技术受到越来越多的关注,它可以为粮食储存提供低温环境,减少外界环境对粮堆的影响,有助于安全储粮。但目前地下仓内粮食在储粮期间结露等问题还未完全解决,深入研究安全储粮问题,探讨粮堆内部温湿度的变化情况,降低粮堆内部发生结露的风险对于保障粮食安全储藏至关重要。本文以小麦粮堆作为研究对象,对地下粮仓在静态储藏和机械通风过程中的结露情况进行了研究。通过搭建地下粮仓的实验平台,分析静态储藏阶段与机械通风阶段粮食堆体内热量传递机制及其水分迁移规律,进而探讨了仓内温度和相对湿度等因素对粮堆内部不同位置结露情况的影响。依据地下粮仓实验平台,结合流体流动和传热传质学相关理论,利用多物理场数值模拟软件建立数学模型,通过设置与实验相同的工况验证数值模型的准确性和可行性后,分别改变静态储藏阶段和机械通风阶段的边界条件,模拟计算了不同初始粮温和不同通风温度条件下粮堆内部温度场的变化情况,得出以下主要结论:(1)在静态储藏阶段,不同的初始粮温会导致粮堆内部温度场分布存在差异进而影响粮堆内部发生结露的风险:当初始粮温低于土壤温度时,粮堆内部温度场分布较为均匀,且不会存在“热芯”区域,能够有效地降低粮堆内部发生结露的风险;当初始粮温高于土壤温度时,粮堆内部的温度场存在明显差异,会形成高温“热芯”区域,增大粮堆内部发生结露的风险。(2)在机械通风阶段,不同的通风温度会影响粮堆内部温度场的分布情况:当通风温度高于或者低于土壤温度时,粮堆中心区域温度变化较为明显,与仓壁处粮食形成明显的温度差,增大粮堆内部发生结露的风险;当通风温度与土壤温度相似时,粮堆内部温度场分布均匀,有效的降低了发生结露的风险。(3)机械通风阶段对空气进行预处理,能够降低通风温度与土壤温度的差异,使粮堆内部温度场分布均匀,结合新风降低粮堆内部相对湿度,有效地降低了粮堆内部发生结露的风险,有助于安全储粮。更多还原

【Abstract】 Grain has played a pivotal role in human survival and societal advancement since ancient times,and food security issues are integral to world peace,development,and the building of a shared human destiny.In recent years,the low-temperature storage technology of underground grain silos has gained significant attention as it provides a low-temperature environment for grain storage,thereby mitigating external environmental impacts on grain piles and addressing food security challenges to a large extent.Nonetheless,issues such as condensation within stored grain remain prevalent,necessitating in-depth studies on safe grain storage,particularly focusing on the variations of temperature and humidity within grain piles and strategies to mitigate the risks of condensation.This paper centers its research on wheat grain piles in underground storage facilities,examining condensation occurrences during both static storage and mechanical ventilation phases.By constructing an experimental platform simulating an underground square-shaped grain silo,the study analyzes the mechanisms of heat transfer and moisture migration within grain piles during the static storage and mechanical ventilation phases.Leveraging multiphysics numerical simulation software,mathematical models are built based on the experimental platform and principles of fluid dynamics,heat transfer,and mass transfer.After validating the accuracy and feasibility of the models under identical conditions,simulations are conducted to calculate the variations in the temperature field within the grain pile under various initial grain temperatures and ventilation temperature conditions.The main conclusions drawn are as follows:(1)During the static storage phase,differing initial grain temperatures lead to variations in temperature field distribution within the grain pile,which in turn influence the risk of condensation occurring within the pile.When the initial grain temperature is lower than the soil temperature,the temperature field distribution within the pile is relatively uniform,lacking a "hot core" region,effectively reducing the risk of internal condensation.Conversely,when the initial grain temperature exceeds the soil temperature,the temperature field within the pile exhibits a significant disparity,forming a high-temperature "hot core," thereby increasing the likelihood of condensation occurring within the grain mass.(2)During the mechanical ventilation phase,different ventilation temperatures impact the distribution of the temperature field within the grain pile.If the ventilation temperature is either higher or lower than the soil temperature,the temperature change in the central area of the pile is more pronounced,creating a marked temperature gradient between the grain near the warehouse walls and the center,thereby escalating the risk of condensation occurring within the pile.However,when the ventilation temperature is similar to the soil temperature,the temperature field distribution within the pile becomes uniform,effectively diminishing the likelihood of condensation events.(3)The mechanical ventilation phase,when coupled with pre-treatment of the air,serves to reduce the differential between the ventilation temperature and the soil temperature,thus ensuring a uniform temperature field distribution within the grain pile.This,along with the introduction of fresh air that lowers the relative humidity inside the pile,significantly mitigates the risk of condensation occurring within the grain mass,thereby contributing to safe storage practices.更多还原