绕管式换热器壳侧汽化模拟时的液滴粒径研究

Study on liquid particle diameter during simulating vaporization of spiral wound heat exchanger shell-side

关键词:  绕管式换热器  剪切流  汽化换热  平均粒子直径  热相变比

Key words:  spiral wound heat exchanger  shear flow  vaporization heat transfer  average diameter of liquid particle  heat ratio of phase change

摘要:

使用ANSYS CFX软件下的欧拉模型对绕管式换热器壳侧乙烷剪切汽化流动进行了数值模拟,对控制方程组中影响相间作用的离散相液滴粒径展开了研究。从能量守恒角度推导出离散液相平均粒子直径公式,通过引入热相变比参数得以简化计算液相平均粒子直径,实现对壳侧剪切流汽化换热过程准确模拟,换热模拟偏差在±20%范围内。壳侧冷剂入口干度和工作压力是影响热相变比的主要因素,以入口干度和汽相密度为自变量对热相变比进行公式拟合,给出了适用于变工况下的热相变比计算式。 

Abstract:

The Euler model that attaches to the ANSYS CFX software is used to simulate the ethane shear and vaporizing flow on the shell-side of spiral wound heat exchanger (SWHE). The diameter of the disperse liquid particle that influences the phase interactions in the governing equations is investigated. Based on the energy conservation, formula for the average diameter of the disperse liquid particle is deduced. The heat ratio of phase change is proposed to compute simply the liquid particle average diameter so that the shear and vaporizing flow on the shell-side of SWHE could be simulated accurately and within the deviation of ±20%. The heat ratio of phase change is mainly influenced by the shell-side operating parameters including inlet quality and pressure, hence a formula of the heat ratio of phase change is fitted by both shell-side inlet quality and vapor density variables. The formula of the heat ratio of phase change is also applicable under different conditions such as mass velocity and heat flux variation.