二甲醚/液化石油气液滴超临界蒸发特性的数值模拟

Numerical Simulation on Supercritical Evaporation Characteristic of DME/LPG Fuel Droplet

引入相平衡理论建立了DME-LPG-N2三元气、液高压相平衡,获得了液滴表面各组分的物质的量分数.建立了混合液滴超临界蒸发的计算模型,计算了二甲醚(DME)/液化石油气(LPG)双燃料液滴的蒸发过程,考察了液滴的初始直径、初始组分、环境温度和环境压力对蒸发过程的影响.结果表明:环境压力、温度越大,环境介质(N2)在液滴中的溶解越明显;液滴初始直径越小,蒸发寿命越短;液滴中DME越多,亚临界蒸发过程中的液滴蒸发寿命越长,而超临界蒸发过程中液滴蒸发寿命越短;环境温度越高,液滴蒸发寿命越短;在研究的温度范围内,环境压力越高,在亚临界条件下液滴蒸发寿命越短,而在超临界条件下液滴蒸发寿命越长.

On the basis of equilibrium theory,the surface equilibrium of multi-component droplet was established to calculate mole fractions of each component on the droplet surface. And the supercritical evaporation model of multi-component droplet was proposed. The evaporation process of DME/LPG mixture droplet was studied. The effects of different initial component and initial diameter of droplet,pressure and temperature of ambient environment on the evaporation of multi-component droplet were studied. The results show that:the evaporation is lower when initial diameter of droplet is larger;and evaporation is faster when ambient temperature is higher. When ambient pressure is lower than the critical pressure,evaporation will get faster if ambient pressure is higher. Under the temperature range studied,when ambient pressure is higher than the critical pressure,the evaporation time will be short. If ambient pressure is lower than the critical pressure,the larger the DME mole fraction is,the longer the evaporation time is.If ambient pressure is higher than the critical pressure,the larger the DME mole fraction is,the shorter the evaporation time is.