(中南大學能源科學與工程學院，長沙 410083)
摘 要: 在鋁電解工藝中，氧化鋁在電解質中的溶解同時受傳熱與傳質的控制。通過建立氧化鋁顆粒溶解的傳熱控制模型、傳質控制模型以及收縮核模型，基于OpenFOAM開源軟件平臺，采用自編程的方法開發(fā)氧化鋁溶解求解模塊，對氧化鋁顆粒在兩種控制機制下的溶解進行數值模擬。結果表明：在傳質機制控制下，其顆粒的質量溶解速率及其速率的變化梯度均隨粒徑的減小而降低；在傳熱機制控制下，其顆粒質量溶解速率也隨顆粒粒徑的減小而減小，但速率梯度變化不大。為了區(qū)分氧化鋁溶解過程中傳熱與傳質兩種控制機制中哪種機制占主導作用，提出臨界直徑的定義及其判定。研究得出氧化鋁顆粒臨界直徑為560 μm，小于560 μm的氧化鋁顆粒溶解受傳質機制的控制，大于560 μm的氧化鋁顆粒溶解受傳熱機制的控制。
關鍵字: 鋁電解；氧化鋁溶解；傳質控制機制；傳熱控制機制；臨界直徑
（School of Energy Science and Engineering, Central South University, Changsha 410083, China）
Abstract:In the aluminum electrolytic process, alumina was dissolved in the electrolyte under the control of both heat and mass transfer mechanism. Heat transfer control model, mass transfer control model and the shrinking core model of alumina dissolution were established, Based on the OpenFOAM open source software platform, alumina dissolution solution module was set up by the custom code. Numerical simulations of the dissolution of alumina particles under the two mechanisms were conducted. The results show that under the control of mass transfer mechanism, the mass dissolution rate and the varying gradient of the mass dissolution rate of alumina particles reduce with decreasing the particle size. Under the control of heat transfer mechanism, the mass dissolution rate decreases with decreasing the particle size, while the varying gradient of the mass dissolution rate shows little change. In order to distinguish the dominance of the heat transfer or mass transfer control mechanism, the definition and judgement of the critical diameter were put forward. Considering the dissolution process of alumina particle is governed by mass transfer as well as heat transfer mechanism together, the critical diameter is 560 μm. The dissolution of alumina particles with the size of less than 560 μm is governed by mass transfer mechanism, while the dissolution of alumina particles with the size of more than 560 μm is under the control of the heat transfer mechanism.
Key words: aluminum reduction; alumina dissolution; mass transfer mechanism; heat transfer mechanism; critical diameter
