具階梯之環狀空間(上半環大於下半環)的熱質自然對流現象之實驗研究

Natural Convection Heat and Mass Transfer in an Annular Enclosure with Step and Smaller Lower Semi-Annular

宋思賢(Szu-Hsien Sung)

指導教授 ： 王立文

元智大學/工程學院/機械工程學系/碩士(2005年)

摘要

具階梯之環狀空間(上半環大於下半環)的熱質自然對流現象之實驗研究
學 生 ：宋思賢 指導教授 ：王立文
元智大學機械工程學系(所)
摘 要
本研究主要是藉由實驗方法來探討幾何形狀為具階梯之環狀空間(上半環大於下半環)的封閉盒，其由溫度梯度與濃度梯度所引起的熱質自然對流現象。外圓環及內圓柱由銅所組成，而階梯則貼上絕緣膠帶，確保電絕緣。利用其幾何形狀與邊界條件的設計，來探討具階梯之環狀空間(上半環大於下半環)對流場結構之影響。
實驗工作流體為濃度0.05M的硫酸銅水溶液( CuS04 + H2SO4+ H2O )。溫度梯度由兩個不同溫度的恆溫水槽維持，濃度梯度則由電化學系統來建立。
對於封閉盒內流場現象，乃是採用雷射光暗影法(shadowgraphy)來觀察流場，並且以數位相機拍照紀錄以利分析。為了瞭解流場結構，對流場的溫度及濃度分佈亦做量測。最後，對於質傳遞率Sh值與Grm、Grt之關係也做量測與分析。

關鍵字

階梯 ； 環狀 ； 熱質自然對流

並列摘要

Natural Convection Heat and Mass Transfer in an Annular Enclosure with Steps and Smaller Lower Semi-Annular

Student：Szu-Hsien Sung Adviser： Lin-Wen Wang

Department of Mechanical Engineering
Yuan-Ze University

ABSTRACT

The purpose of the study is to investigate flow patterns, temperature and concentration distributions resulting from buoyancy force due to a combination of temperature and species convection effects in an annular enclosure with steps and smaller lower semi-annular.
In this experiment, the temperature and the concentration differences are made between the inner cylinder and the outer annular. Cupric Sulphate solution is selected as the working fluid. Two constant temperature baths keep the temperature gradient. The concentration gradient is controlled via electrochemical system. The temperature and concentration gradients are imposed in such a way that their effects on the flow were either cooperating or opposing.
In order to visualize the flow, the shadowgraph technique is used. Electrical measurements will be used to obtain mass transfer rates and to infer a Sherwood number.
To understand the flow structure, the temperature distribution and concentration distribution are investigated. Finally, the correlations between Sherwood number and solutal concentration Grashof number and thermal Grashof number are also needed to be analyzed.

並列關鍵字

step ； annular ； thermosolutal convection