แบบจำลองเชิงประจักษ์ขนาดความหนาของฟิล์มของเหลวของการไหลแบบวงแหวนระหว่างแก็สและของเหลวในท่อแนวดิ่ง

Abstract

This thesis establish a database of experimental results of liquid film thickness in vertical annular flow. A total of 8 experimental results were collected from different experimental groups, which measured the liquid film thickness covering the conditions of annular flow. And propose a mathematical model to predict the liquid film thickness in the vertical annular flow. Annular flow is described as high velocity of gas flow in pipe center and liquid is flowing low velocity around pipe wall. When the velocity of gas is very high, interfacial shear stress increases and shear the surface of fluid drops into gas core flow. Annular flow is more efficient of heat transfer than other types of flow. The high heat transfer efficient occurs when the transition from liquid to gas. Annular flow has liquid film thickness that affects heat transfer efficiency. When thin liquid film thickness affects good heat transfer performance. But if the liquid film thickness is too thin to evaporate, all the gas will cause little or no heat transfer. The comparison of empirical and semi-empirical models to predict the liquid film thickness film under the database from 8 different experimental groups. The mean relative absolute error is 22.55% and 20.78%. Both of models predict the liquid film thickness better than other models under the created database conditions.