绝热状态下板壳式换热器壳侧的流型与压降

实验研究了板壳式换热器波纹通道内垂直向上气-液两相流动的流型和压降特性，讨论了圆形波纹通道内流型特征及转变机理，根据相界面形态特征将流型划分为泡状流、弹状流、膜状流和搅混流；同时分析了流型与压降之间的关系，发现泡状流中的压降波动幅值最小，弹状流与膜状流次之，搅混流中压降波动幅值最大；获得了波纹通道内单相以及气-液两相压降的分布规律，拟合了单相压降关联式，并基于Lockhart-Martinelli理论，通过分析两相摩阻系数与Martinelli参数的关系拟合了波纹通道内两相流动压降关联式，发现Chisholm参数C的值与Chisholm最初建议的光滑管内层流-层流的值接近。

Flow pattern and pressure drop on shell side of shell and plate heat exchanger under adiabatic state

The heat exchanger is one of the main equipment in the field of petroleum, chemical industry, nuclear energy and other industrial applications. The development of an efficient heat exchanger can effectively improve the energy utilization rate, which is an important way to solve the energy and environmental problems. Shell and plate heat exchanger is a new type of heat exchanger; it combines the advantages of shell and tube heat exchanger and plate heat exchanger. It has high heat transfer efficiency, high temperature and pressure resistance, compact structure and light weight, and makes up for the uneven stress distribution of plate heat exchanger. At present, there are few literature reports on the flow pattern and pressure drop characteristics of gas-water two-phase flow in the shell and plate heat exchanger. In this paper, the flow pattern and pressure drop of the vertical upward gas-liquid two-phase flow in the shell and plate heat exchanger are experimentally studied. The macro distribution characteristics of the vertical upward gas-water two-phase flow interface in the shell and plate heat exchanger are obtained by high-speed camera technology. The flow pattern is divided into bubbly flow, slug flow, film flow and churn flow according to the morphological characteristics of the phase interface; at the same time, the relationship between flow pattern and pressure drop is analyzed, and it is found that the amplitude of pressure drop fluctuation in bubble flow is the smallest, followed by the slug flow and the film flow, and the amplitude of pressure drop fluctuation in the agitated flow is the largest; based on Lockhart-Martinelli theory, the prediction model of two-phase flow pressure drop in the shell and plate heat exchanger is established by analyzing the relationship between two-phase multiplier and Martinelli parameter, it is found that the value of Chisholm parameter C is close to the value of Chisholm's original laminar-laminar flow in smooth tube.