具不規則階梯之環狀封閉盒的熱質自然對流實驗研究

Natural Convection Heat and Mass Transfer in an Annular Enclosure with Irregular Steps

廖彧瑋(Yu-wei Liao)

指導教授 ： 王立文

元智大學/工程學院/機械工程學系/碩士(2006年)

https://doi.org/10.6838/YZU.2006.00058

摘要

本實驗採用以實驗的方法在環狀空間中引入不規則階梯空間的封閉盒，並探討其對溫度梯度以及濃度梯度所引起的熱質自然對流現象。
實驗所用工作流體為濃度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，其溫度梯度約介於15-30℃，濃度梯度則由電化學系統來建立，於銅加上端電壓，使其成為電極造成濃度梯度。並利用雷射光暗影法來觀測流場狀態。
其中在內熱外冷順向的流場當中，可以見到在階梯部分有迴流區的現象產生；而在內熱外冷逆向的情形，則觀察到陽極較重的流體在階梯前端產生有分離現象，並出現不連續的interface產生。
最後可知在固定Grm的情況下，當Grt增加時，無因次質傳遞率會隨之增加；且在相同Grt時，順向流場的無因次質傳遞率會比逆向流場時的大。

關鍵字

階梯,熱質對流

並列摘要

The purpose of the study is to investigate flow patterns, temperature and concentration gradients resulting from buoyancy force due to a combination of temperature and species convection effects in an annular enclosure with irregular steps.
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 an 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. Also the effect of the steps will be investigated very carefully.

並列關鍵字

step,thermosolutal

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