论文部分内容阅读
真空闪蒸喷雾冷却是利用液体工质在真空环境下相变吸热来冷却加热表面的新型冷却手段。具有散热能力强、所需工质少,与加热表面没有接触热阻等优点,在航天器电子元器件冷却方面具有广阔的应用前景。液滴闪蒸是真空闪蒸喷雾冷却闪蒸过程的重要组成部分,要研究整个真空闪蒸喷雾冷却系统的闪蒸过程就必须对液滴的闪蒸特性进行研究。本文考虑液滴闪蒸过程中液滴内部存在的温度梯度和对流的影响,采用扩散控制蒸发模型并结合导热方程,对液滴的热导率进行修正,建立了热导率修正模型计算直径为微米级液滴在毫秒量级时间内的真空闪蒸特性,并通过实验验证。研究结果表明,导热模型较等温模型能更准确地预测液滴温度的变化;液滴闪蒸导致液滴到达被冷却表面时,其温度下降明显,但体积几乎没有变化;并且,环境压力越低,液滴的初始半径越小,液滴速度越大,液滴闪蒸对液滴温度的影响越明显。
Vacuum flash spray cooling is the use of liquid refrigerant in the vacuum environment phase change endothermic to cool the heating surface of the new cooling means. Has a cooling ability, the required working fluid less, no contact with the heating surface thermal resistance, etc., in spacecraft electronic components cooling has broad application prospects. Droplet flash evaporation is an important part of vacuum flash spray cooling flashing process. To study the flash evaporation process of the entire vacuum flash spray cooling system, the flash characteristics of liquid droplets must be studied. In this paper, the influence of temperature gradient and convection inside the droplet during the droplet flashing process is considered. The diffusion-controlled evaporation model is combined with the thermal conductivity equation to modify the thermal conductivity of the droplet. The thermal conductivity correction model is established to calculate the diameter Micro-level droplets in milliseconds vacuum flash characteristics of the time, and through experimental verification. The results show that the thermal model can predict the droplet temperature more accurately than the isothermal model. When the droplet reaches the surface to be cooled, the droplet temperature drops obviously, but the volume hardly changes. And the lower the ambient pressure , The smaller the initial radius of the droplet, the greater the droplet velocity, and the more obvious the influence of the droplet flash on the droplet temperature.