水平等溫二相管流中流場型態的觀測

• Main Author: 林存國
• Other Authors: 游明輝
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/02605446951777505509

碩士 === 國立中山大學 === 機械工程研究所 === 83 === 　　This paper aims to investigate isothermal two-phase flow in horizontal pipes by experimental methods to identify a variety of flow patterns, the characteristics of flow behavior, and to compare flow patterns under various geometries inside tubes. Because flow patterns are related to the rate of heat transfer, the study is to provide fundamentals for the design of evaporator and condenser for a high-performance air-conditioning system. The parameters to control experimental conditions include air and water flow rates at inlet, configuration and size of enhanced surface. The experiment involves flow visualization to observe the growing, breakdown, and distribution of bubbles in the two-phase flow field, and measurements of wall pressure to compare the pressure drops of different flow patterns in various types of enhanced tubes. The experimental results indicate that there are six flow patterns including bubbly flow, plug flow, stratified flow, wavy flow, slug flow and annular flow in a smooth tube; there are six flow patterns in an enhanced tube with square finned inserts, and mixed flow patterns (e.g. plug and bubbly flow, slug and bubbly flow, stratified and bubbly flow); there are four to five flow patterns in enhanced tubes with spiral inserts, where the separated flow patterns (stratified flow, wavy flow) are not observed under the range of the experimental parameters. In addition, from transitions of flow patterns in the tubes we used, we acquire the maximum trend of heat transfer enhancement in a tube with 23mm inner diameter and spiral inserts of 19mm pitch, but the pressure drop of this tube is maximum.