The Investigation On Fine Water Mist Cooling For Regulation In Large Space Of Local Environment

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.