室内微生物气溶胶蒸发特性影响研究

发布时间：2018-05-20 16:04

本文选题：液滴蒸发 + 平板液滴蒸发　；参考：《西安建筑科技大学》2017年硕士论文

【摘要】：人们的日常生活和工艺操作的各个流程中均会产生大量的液态颗粒物,当这部分液态颗粒物的粒径范围在0.001~100μm之间时,就可以悬浮在空气中,与空气组成的多相体系我们称为大气气溶胶。悬浮于空气中的液态颗粒物可能包含有各类离子和微生物,对环境造成程度不一的污染,当液态颗粒物中夹带的微生物为致病菌时还会成为威胁人类健康的重要隐患。悬浮于空气中的液态颗粒的蒸发现象使得其受力处于一个动态变化的过程,因此研究液态颗粒物的蒸发过程对合理有效地预测及控制其分布具有重要意义。目前对于单个液态颗粒物蒸发过程的研究多集中在数值模拟方法的探讨,理论公式的推导等方面,对毫米级的大液滴和微米级的小液滴分别提出了不同的蒸发模型;液态颗粒物蒸发过程的实验研究较少,目前的主要实验方法包括液滴悬挂法、多孔球法、飞滴实验法及气悬(磁悬)法,研究发现液滴中包含有其余组分时蒸发过程可分为两个阶段,液滴在平板上蒸发时蒸发状况视其接触线是否钉扎而定。基于此,本文对常温常压建筑室内环境下液态颗粒物的蒸发过程设计了简单的实验系统,采用平板液滴蒸发的方式,通过称量液滴蒸发过程中的质量变化说明了微生物悬浮液液滴的蒸发特性。实验及结论主要包括三部分内容:(1)不同体积纯水液滴的蒸发实验,本文首先分别分析研究了1μL、2μL和5μL的液滴在超疏水涂层玻片上进行蒸发时的质量变化和形态变化,分析了液滴在平板上蒸发时的两阶段现象,提出了在常温常压的建筑室内环境下液滴粒径对蒸发的影响;(2)结合第一部分研究内容选定了后续实验采用的液滴体积,对NaCl溶液液滴进行了蒸发实验研究,发现溶液中离子的存在将使得液滴蒸发速度显著降低,蒸发阶段结束后玻片上的残留物直观反映了液滴在超疏水玻片上蒸发时将产生的“咖啡环效应”;(3)对添加有不同微生物的溶液液滴进行了蒸发实验研究,结果显示液滴中含有微生物时蒸发可分为蒸发阶段和平衡阶段,不同种类的微生物溶液液滴蒸发过程的蒸发阶段时刻不同,平衡阶段质量波动范围不同。本文研究结果显示微生物的存在对液滴的蒸发将产生较强影响,对预测室内微生物气溶胶的蒸发运动过程具有重要意义,为设计布置合理的空气净化系统提供了理论依据。
[Abstract]:People's daily lives and processes produce a lot of liquid particulate matter, which can be suspended in the air when the particle size of the liquid particle is in the range of 0.001 ~ 100 渭 m. A heterogeneous system consisting of air is called an atmospheric aerosol. Liquid particles suspended in the air may contain various kinds of ions and microbes, which cause varying degrees of pollution to the environment. When the microorganism contained in the liquid particles is a pathogenic bacteria, it will also become an important hidden danger to human health. The evaporation of liquid particles suspended in air makes its force change dynamically. Therefore, it is important to study the evaporation process of liquid particles in order to predict and control their distribution reasonably and effectively. At present, the research on the evaporation process of single liquid particle is mainly focused on the discussion of numerical simulation method and the derivation of theoretical formula. Different evaporation models are put forward for large liquid droplets of millimeter size and small droplets of micron size respectively. There are few experimental studies on the evaporation process of liquid particles. At present, the main experimental methods include droplet suspension method, porous sphere method, flying drop test method and gas suspension (magnetic suspension) method. It is found that the evaporation process can be divided into two stages, and the evaporation condition depends on whether the contact line is pinned or not. Based on this, this paper designed a simple experimental system for the evaporation process of liquid particulate matter in the indoor environment of normal temperature and atmospheric pressure building, adopting the method of flat droplet evaporation. The evaporation characteristics of microbial suspensions were explained by the mass change in the evaporation process of weighing droplets. The experiment and conclusion mainly include three parts: the evaporation experiment of pure water droplets with different volumes. In this paper, the mass and morphology changes of droplets of 1 渭 L ~ (2 渭 L) and 5 渭 L on superhydrophobic coating glass are studied respectively. The two-stage phenomenon of droplet evaporation on the flat plate is analyzed, and the effect of droplet size on evaporation in the indoor environment at room temperature and atmospheric pressure is put forward.) in combination with the first part of the study, the volume of the liquid droplet used in the subsequent experiments is selected. The evaporation experiments of droplets in NaCl solution were carried out. It was found that the evaporation rate of droplets would be significantly reduced by the presence of ions in the solution. The "coffee ring effect" produced when the droplet evaporates on the superhydrophobic glass is directly reflected by the residue on the glass after the evaporation stage. The experimental study on evaporation of liquid droplets with different microbes was carried out. The results show that the evaporation of droplets containing microbes can be divided into evaporation stage and equilibrium stage. The evaporation time of droplet evaporation in different kinds of microbial solutions is different, and the range of mass fluctuation in equilibrium phase is different. The results show that the existence of microbes will have a strong influence on the evaporation of droplets, which is of great significance for predicting the evaporation process of indoor microbial aerosols, and provides a theoretical basis for the design and arrangement of a reasonable air purification system.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X513

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