基于液滴分析的高温高压流体喷射闪蒸模型研究

Modeling of Spray Flash Evaporation under High Temperature and High Pressure Based on Droplet Analysis

为加深对核电站一回路冷却剂泄漏相关的高参数流体喷射闪蒸特性的理解,本文采用模型计算的方法对高温高压流体喷射闪蒸热力学特性进行研究。本文模型综合考虑了液滴运动、液滴传热传质及液滴物性变化,计算分析了液滴温度分布、闪蒸效率及喷射闪蒸强度的变化。研究结果表明:提高过热度可有效降低液滴完成闪蒸所需的距离,并在大范围内提高闪蒸效率;减小液滴尺寸会导致同一位置处的液滴无量纲温度明显降低;流速变化主要影响液滴温度的空间分布,对液滴温度的时间分布几乎无影响;流速增大导致一定空间内的闪蒸效率降低;相比液滴尺寸变化对无量纲温度分布的影响,改变液滴尺寸对闪蒸效率的影响程度相对较小;液滴尺寸及过热度对喷射闪蒸强度的影响有个转折点,流速增加导致转折距离相应增大。

In order to deepen the understanding of flash evaporation characteristics related to the coolant leakage under high-parameter conditions in the primary circuit of nuclear power plant,the thermodynamic characteristics of spray flash evaporation under high temperature and high pressure were studied based on the modeling method in this paper.The droplet motion,droplet heat and mass transfer and physical properties change were comprehensively considered in this model.The droplet temperature distribution,flashing efficiency and intensity of spray flash evaporation were calculated and analyzed.The results show that increasing the superheat can effectively reduce the distance needed for the finish of the flash evaporation and improve the flashing efficiency in a wide range.The decrease of the droplet size can lead to the obvious decline of the dimensionless temperature at the same position.The flow velocity mainly affects the spatial distribution of the droplet temperature and has little effect on the temporal distribution of the droplet temperature.The flashing efficiency decreases with the increase of the flow velocity within a certain area.Compared with the effect of the droplet size on the dimensionless temperature distribution,the effect of the droplet size on the flashing efficiency is relatively small.The effect of the droplet size and superheat on the intensity of spray flash evaporation has a turning point.The turning distance increases with the flow velocity.