- 學位論文
反向三角形密封盒內熱質自然對流現象研究
The Study of Thermosolutal Convection in a Reverse Triangle Enclosure
摘要
本研究是利用實驗的方法來探討幾何形狀反向三角形密閉盒，由溫度梯度與濃度梯度所引起之熱質自然對流現象。並且改變其邊界條件之設計，使得在實驗中可觀察到，不同邊界條件之反向三角形空間對於流場型態之影響。並且針對不同流場型態，量測溫度與濃度分佈，近而了解流場結構。並對於質傳遞率Sh值與Grm，Grt之關係作分析。 實驗工作流體為濃度0.05 M的硫酸銅水溶液(CuSO4+H2SO4+H2O)。 溫度梯度是由兩個不同溫度的恆溫水槽來維持。濃度梯度則利用電化學系統來建立，既利用電解方式在壁面造成不同濃度的擴散邊界層。流場觀察是利用雷射光暗影法(shadowgraph)，並且以相機拍照紀錄。 本研究中發現，Sh值隨著Grt的增加而增加。在整理後發現水平壁決定了流場形態、溫度與濃度分佈，且當水平壁為絕緣時可觀察到堆積的流體會發生被帶離的現象。
並列摘要
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 a reverse triangle enclosure. In this experiment, the temperature and the concentration differences are made between the two walls of three walls in the triangle enclosure. 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. In this experiment, the Sh value increases with the Grt increase. After the rearrangement, we are found that the horizontal wall decides the flow structure, the temperature and the concentration distribution. But when the horizontal wall is insulated the stack flow can be observed and it will cause a phenomenon of being brought to leave.