【作者】 屠欣丞；

【导师】 王军锋；

【作者基本信息】 江苏大学 ， 流体机械及工程， 2009， 硕士

【摘要】 全球变暖和空气污染是人类当前面临的两大严重环境问题,城市高温所带来的夏季能耗问题逐渐突出。细水雾蒸发降温具有节能环保、无污染的优点,可用于大空间局域环境的调节。本文围绕该技术对细水雾气液两相流动和大空间局域环境调节进行数值模拟和实验研究。针对细水雾大空间局域环境调节的关键问题,进行了以下探索:(1)对不同粒径尺寸液滴在非稳态蒸发过程中的传热传质规律进行研究。通过分析单液滴非稳态蒸发过程的数学模型,对不同粒径尺寸的雾滴在室外环境中的蒸发过程进行了数值求解,分析液滴表面温度、液滴直径随时间变化的发展规律,获得了液滴非稳态蒸发时间与液滴寿命之间的关系。(2)对大空间局域环境降温增湿的模拟技术进行了探索。应用FLUENT软件对大空间局域环境的喷雾两相流场进行数值模拟,分析了不同雾化参数和气相参数下的温度场和湿度场。对人体感知区域的温湿度分布进行对比分析,获得了细水雾在大空间局域环境条件下弥散、蒸发的一般规律。(3)建立射流式低压旋流雾化降温系统和立柱式高压雾化降温系统,对细水雾在大空间局域环境条件下的降温效果和输运特性进行实验研究,获得了不同雾化参数和气相参数对大空间局域环境降温效果的影响规律。优化了高压雾化降温系统中的喷嘴布置;将实验结果和数值模拟结果进行了对比分析研究。(4)提出喷雾降温调节系统的设计方法,建立了细水雾大空间局域环境调节的数学模型。根据建立的细水雾大空间局域环境弥散输运数学模型,分析了半室外环境降温过程中环境湿度的变化规律,通过设定配风量和降温终端的工作频率来控制环境中的湿度变化,使降温空间的相对湿度能够保持在容许范围之内。通过对不同降温形式能耗的比较,分析了细水雾大空间局域环境降温的节能效果。(5)提出以人体舒适度指数作为评价细水雾降温系统性能及调节效果的依据,将细水雾环境降温效果进行量化,为大空间局域环境调节提供了研究方法和理论基础。应用人体舒适度指数模型对降温后的局域环境进行人体舒适度分析,验证了细水雾大空间局域环境调节技术的可行性。将降温前后的人体舒适度指数进行对比后发现:细水雾大空间局域环境调节技术能够改变局域环境的人体舒适度指数,环境质量得到明显改善。更多还原

【Abstract】 The global warming and air pollution have become the two most serious problems. The effect of high temperature in summer on energy consumption of cooling is increasing. The fine water mist regulation in large space of local environment is a type of non-emission and environmentally-benign technology. Based on a series of experimental study and numerical simulation, the gas-liquid two-phase flow of fine water mist and regulation in large space of local environment are studied in this dissertation. In view of the main problems of the fine water mist regulation in large space of local environment, we carried out the study as follows:(1) The heat and mass transfer characteristic of droplets with different diameter in the unsteady evaporation period is investigated. Based on the analysis of unsteady evaporation mathematical model of single droplet, the numerical analysis on evaporation of droplets with different diameter is proposed. After the discussion of evolution of surface temperature and diameter of single droplet, the correlation of droplets lifetime and unsteady evaporation period is analyzed.(2) The numerical simulation of fine water mist cooling and humidity adjusting in large space of local environment is presented. Based on the simulations of two-phase flow field of spray cooling in large space of local environment is finished by using software FLUENT, the effect of different atomization parameters and gas-phase parameters on temperature field and humidity field is analyzed. According to the discussion of temperature and humidity distribution on the vertical axial cross sections and horizontal plane that a human being could sense, the dispersion and evaporation of fine water mist in large space of local environment is obtained.(3) The experimental systems of low pressure swirl spray cooling and pillar design high pressure spray cooling are adopted to study the spray cooling effect and mass flux of fine water mist in large space of local environment. The experiment is conducted for the effect of different atomization parameters and gas-phase parameters on the cooling effect of large space of local environment and the arrangement of nozzles of high pressure cooling system is optimized. Some of the experimental results are compared with the numerical simulation results. The mass flux and diffusion of fine water mist in the space is described and investigated.(4) A mathematical model of cooling, humidity adjusting and humidity regulation in large space of local outdoor/semi-outdoor environment is established in this dissertation. The design method of system that has the function of cooling, relative humidity adjusting and regulation in humidity is proposed. According to the dispersion and transportation model of fine water mist, the evolution of humidity of environment and the water mist evaporation mass flow rate are studied. The evolution of humidity of environment is controlled by setting the ventilation rate and the performance frequency of cooling system and the humidity of environment would be maintained at a comfortable level. The effect of energy saving of spray cooling is analyzed by comparing the energy consumption of different cooling methods.(5) In order to quantify the spray cooling effect, the human comfort index is put forward as the basis of evaluation for performance and effect of fine water mist cooling system. The human comfort index model is adopted in the analysis of human comfort of cooling space to validate the feasibility of fine water mist cooling for regulation in large space of local environment. Based on the comparison of human comfort index around the spray cooling, the fine water mist regulation in large space of local environment would descend the human comfort index of local environment. The quality of environment should be improved significantly. It provides the regulation in large space of local environment with research method and theoretical basis.更多还原