- 學位論文
雙圓環(六分之一外環局部導熱)密閉容器的質熱對流研究
Thermosolutal Convection in Annular Enclosure with Partially Conductive Outer-Cylinder
摘要
本文主要是藉由實驗方法來探討幾何形狀為雙圓環密閉容器，由溫度梯度與濃度梯度所引起的質熱自然對流現象。利用其幾何形狀與邊界條件的設計，使得在實驗中可以觀察到外環局部導熱對於雙圓環密閉容器中流場的影響，本次的實驗的模型設計為六分之一的外圓環及內圓柱由銅所組成，一又三分之二的外圓環由壓克力所組成。並針對相關無因次參數來探討密閉區域內的流場型態。 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，於外圓環及內圓柱兩端加入極限電流，使其成為電極造成濃度梯度。 對於雙圓環密閉容器的流場現象，是採用雷射光暗影法(shadowgraphy)來觀察流場，並且以相機拍照紀錄，以利分析；為了瞭解流場結構，對流場的溫度及濃度分佈作測量，最後，對於質傳遞率Sh值與Grm、Grt之關係做分析。
關鍵字
雙圓環密閉容器的質熱對流研究並列摘要
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 an annular enclosure. In this experiment, the temperature and the concentration differences are made between the inner and the outer cylinder. 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.