SK扰流器液氮泡沫发生装置混合换热性能研究  

Research of mixing and heat transfer performance of liquid nitrogen foam generator with SK spoiler

作　　者：路頔 王丽晶 LU Di;WANG Lijing(Shanghai Fire Research Institute of MEM,Shanghai 200032,China)

机构地区：[1]应急管理部上海消防研究所,上海200032

出　　处：《中国安全生产科学技术》2024年第6期111-117,共7页Journal of Safety Science and Technology

基　　金：应急管理部消防救援科技计划项目(2020XFZD09);应急管理部上海消防研究所科技计划项目(22SX20)。

摘　　要：为提高液氮泡沫发生装置混合发泡性能、缓解冰堵,探究SK扰流器混合换热特性,开展数值模拟并进行实验验证。通过锥形、SK扰流器对不同液氮流速、间距、形状参数的数值仿真对比分析出口氮气体积分数、变异系数以及沿程温度,并通过因子效应极差分析对比长径比、单元数、间距对混合均匀性的影响效应。研究结果表明:SK扰流器相比于锥形扰流器,通过引入旋流破坏流动分层,变异系数下降83%,气液混合和换热性能大幅提高。此外,随着液氮流量增大,管内局部低于冰点容易形成冰堵,建议最大流量比位于1∶33~1∶50之间。随着液氮射流与扰流器间距增大,液氮汽化率下降,出口氮气体积分数和速度相应降低,10 mm间距效果更优。在300 mm扰流器长度下,随着扰流器长径比减小,混合均匀性先提高后下降,压力损失逐渐增大;综合考虑压力损失和混合均匀度,最优长径比约为0.75;长径比因子对变异系数影响较大。研究结果可为液氮泡沫发生装置设计提供指导,提高泡沫发泡性能。In order to enhance the mixing and foaming performance of the liquid nitrogen foam generator and mitigate the issue of ice blockage,the numerical simulation was conducted followed by experimental validation to study the mixing and heat transfer characteristic of SK spoiler.Through the numerical simulation and comparative analysis of different liquid nitrogen flow velocity,spacing,and shape parameters of the cone spoiler and SK spoiler,the outlet nitrogen volume fraction,coefficient of variation,and temperature along the way were studied.Additionally,the effects of aspect ratios,number of units,and spacing on mixing homogeneity were compared using the range analysis for factor effects.The results show that the SK spoiler,compares to the cone spoiler,significantly improves the gas-liquid mixing and heat transfer performance by introducing the swirling flow to disrupt flow stratification,resulting in an 83%reduction in the coefficient of variation.Furthermore,as the flow rate of liquid nitrogen increases,the local sub-freezing conditions within the pipe can lead to ice blockage,suggesting the maximum flow rate ratio ranging from 1∶33 to 1∶50.With the increase in the distance between liquid nitrogen jet and spoiler,the vaporization rate of liquid nitrogen decreases,leading to the corresponding reduction in the outlet nitrogen volume fraction and velocity,and the effect is better under 10 mm spacing.Under the spoiler length of 300 mm,the mixing homogeneity increases first and then decreases with the decrease of spoiler aspect ratio,while the pressure loss gradually increases.Comprehensively considering the pressure loss and mixing homogeneity,the optimal aspect ratio is 0.75,and the aspect ratio has a significant impact on the coefficient of variation.The research results can provide guidance for the design of liquid nitrogen foam generator and enhancing the foaming performance.

关 键 词：液氮 泡沫 SK扰流器 数值模拟 

分 类 号：X937[环境科学与工程—安全科学] X932