Study On Characteristic Of Fine Mist And The Cooling Effect In Long And Narrow Space

Liquid atomization is an important issue in many fields such as energy, power, aerospace, agriculture, chemical and environment engineering. In many kinds of liquid spray nozzles, pressure nozzle has been widely used in engineering for its advantages of simple structure, good atomization performance, low energy consumption and so on. In the case of long and narrow space where a great deal of heat producing, it is feasible to use fine mist as an assistant means to lower the temperature. Presently there are not many researches on this subject, in this way, this dissertation mainly studies on the characteristics of fine mist and its cooling effects in long and narrow space as follows:First, mathe(?)atic and physical model of droplet evaporation is developed and solved. Droplet lifetime (evaporation time) in air is analyzed with the model. By calculating two examples, variation rule of unsteady-state time is obtained, as well as the variation rule of the temperature and diameter of droplet with the ambient temperature. The mechanism of fine mist cooling is analyzed based on the effective film theory.The flow rate characteristic and the atomization performance of several common pressure nozzles are studied, and main factors influencing the nozzle's performance are analyzed. The conclusion shows that characteristics of nozzles in this kind are mainly depended on its dimension and operating parameters. Flow rate correlations formulas and experimental formulas of droplet diameters of these pressure nozzles are first regressed, and the flow rate coefficients of these nozzles are derived accordingly. The variation rules of droplet diameters with spray pressures of one kind of spiral nozzle are studied and the value of critical spray pressure of this nozzle is derived.Rules of temperature distribution with ventilation volume, inlet air temperature, heat intensity and spray volume in long and narrow space are obtained through CFD simulation, and the simulation results are validated by experiment. According to...