温度和压力对液氨闪沸喷雾特性的影响

Effects of Temperature and Pressure on the Flash Boiling Spray Characteristics of Ammonia

摘要:

氨作为一种绿色储氢燃料具有巨大的应用潜力，但液氨沸点低，其在标准大气压下沸点仅为239.7 K，极易发生闪沸。本文在欧拉-拉格朗日框架下，对液氨燃料进行数值模拟，研究其在不同过热度、喷射压力、燃料温度和环境温度下的闪沸喷雾的形态、贯穿距、粒径和氨蒸汽质量分数等特性。结果表明：液氨过热度越大，其喷雾的贯穿距越大，喷雾前端坍缩发生越明显；喷射压力越大，液氨喷雾坍缩先增强后减弱，喷雾的粒径越小；液氨喷雾特征受环境温度影响较弱，在低燃料温度下，喷雾的特征受过热度的影响小，相反，高燃料温度下氨蒸汽质量分数随着温度的升高而增加。

Abstract:

Ammonia is used as a green hydrogen storage fuel with great potential for application， with zero carbon emissions compared to traditional hydrocarbon fuels. Liquid ammonia has a low boiling point of only 239.7 K at 1 atm， which makes it highly susceptible to flash boiling. In this paper， numerical simulations of liquid ammonia fuel were carried out in the Eulerian-Lagrangian framework to investigate the morphology， penetration distance， particle size and ammonia vapor mass fraction of the flash-boiling sprays at different superheat degrees， injection pressures， fuel temperatures and ambient temperatures. The results show that the spray penetration increases with the larger superheat of liquid ammonia， and the collapse of the spray front becomes more pronounced. The higher the spray pressure， the liquid ammonia collapses are enhanced and then weakened， and the particle size is smaller. The spray characteristics of liquid ammonia are almost independent of the ambient temperature， and are less affected by superheat degree at low fuel temperatures， and the opposite is true at high fuel temperatures. The ammonia vapor mass fraction increases with increasing fuel temperature.