Şahin İbrahim, Özbakır Yaprak, İnönü Zeynep, Ulker Zeynep, Erkey Can
Department of Chemical and Biological Engineering, Koç University, Rumelifeneri Yolu, Sarıyer, Istanbul 34450, Turkey.
Department of Pharmacy, Altınbaş University, Mahmutbey Dilmenler Caddesi, No: 26, Bağcılar, Istanbul 34217, Turkey.
Gels. 2017 Dec 29;4(1):3. doi: 10.3390/gels4010003.
Supercritical drying of gels is considered as the most important step of aerogel production since it enables preservation of the three-dimensional pore structure which lead to unique material properties such as high porosity, low density, and large surface area. An understanding of the kinetics of supercritical drying is necessary to provide insight into material development, scale-up, and optimization of the aerogel manufacturing process. Thus, investigation of supercritical drying is gaining increased attention in recent years. This review paper covers the experimental considerations and techniques to study the kinetics of supercritical drying, fundamental mass transfer mechanisms during the drying process and modeling efforts to predict the drying kinetics for varying operating conditions and gel properties. Transport phenomena involving diffusion, convection, spillage by volume expansion, and axial dispersion are discussed by providing the fundamental equations and empirical correlations to predict transfer coefficients. A detailed review of literature covering experimental and theoretical studies on kinetics of supercritical drying is presented.
凝胶的超临界干燥被认为是气凝胶生产中最重要的步骤，因为它能够保留三维孔隙结构，从而产生诸如高孔隙率、低密度和大表面积等独特的材料特性。了解超临界干燥的动力学对于洞察材料开发、放大生产以及气凝胶制造工艺的优化至关重要。因此，近年来对超临界干燥的研究越来越受到关注。这篇综述文章涵盖了研究超临界干燥动力学的实验考量和技术、干燥过程中的基本传质机制以及用于预测不同操作条件和凝胶特性下干燥动力学的建模工作。通过提供预测传递系数的基本方程和经验关联式，讨论了涉及扩散、对流、体积膨胀溢出和轴向扩散的传输现象。本文还对有关超临界干燥动力学的实验和理论研究的文献进行了详细综述。
