绕管式换热器双层分配器流体分配机理与特性OA

A spiral-wound heat exchanger is the core component of a natural gas liquefaction system,and the uniform distribution of its shell-side medium is a critical factor controlling the heat exchange efficiency.The imperfect structural design of the distributor of the spiral-wound heat exchanger may result in non-uniform distribution of medium,thereby directly affecting the performance and energy consumption of the heat exchanger.This paper presents the dual-layer distributor for a spiral-wound heat exchanger.A 3D numerical model of the distributor is constructed using volume of fluid(VOF)multi-phase flow model and Realizable k-ε turbulent flow equations,and it is validated through cold model experiments.Furthermore,the core properties(e.g.internal liquid level,flow coefficient,and distribution uniformity)of the distributor at various flow rates are systematically investigated.The following results are obtained.First,the internal liquid level is linearly and positively correlated with the flow rate.Second,the average flow coefficients of the upper and lower ring-shaped perforated plates are 0.719 and 0.789,respectively,and remain stable under different Reynolds numbers,showing an efficient and steady outflow efficiency.Third,the relative deviation of the flow rate on perforated plates is relatively small(0.96-1.05)at the flow rates ranging from 2.75 m3/h to 4.30 m3/h,suggesting a good distribution uniformity.Fourth,the standard deviation of the flow rate declines with the rising flow rate,and it is always less than 0.026,indicating that the dual-layer structure can significantly enhance the uniform distribution.It is concluded that the dual-layer distributor can effectively improve the distribution uniformity of shell-side medium in the spiral-wound heat exchanger,and improving the heat exchange efficiency and operational stability.The research offers a reference for optimization of equivalent distributors of cryogenic heat exchangers.Subsequent efforts should be made on dynamic properties and long-term operating performance depending on actual working conditions.