Moisture Transport in Unconsolidated Porous Media During Drying: Use of Nuclear Magnetic Resonance Imaging as an Experimental Probe

干燥过程中松散多孔介质中的水分传输：使用核磁共振成像作为实验探针

• 批准号: 8812870
• 负责人: Stephen Whitaker
• 金额: $ 15万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-10-01 至 1991-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8812870&HistoricalAwards=false
• 关键词: Moisture; Transport; Unconsolidated; Porous; Media

This proposal presents a program of theoretical and experimental work directed toward a predictive theory of drying. The influence of local heterogeneities is incorporated into both the theoretical framework and the experimental measurements that were proposed. The theoretical analysis is based on the method of large-scale averaging and a closure scheme that incorporates the effect of local heterogeneities. The experimental studies make use of nuclear magnetic resonance imaging (NMRI) to both quantify the heterogeneities in a porous medium and to measure the local volume averaged saturation during drying. Determination of the spatial variation of the local volume averaged saturation will provide experimental values of the large-scale spatial deviation of the saturation. These in turn, will be compared with predictions from the closure calculations. The key feature of the method of large-scale averaging is the appearance of large-scale spatial deviations in the velocity and concentration, and the existence of a closure scheme that can predict these spatial deviations. In all previous studies of transport phenomena in porous media, theory and experiment have been compared in terms of measured and predicted effective transport coefficients. With the use of NMRI, the PI's are in a position to develop the comparison beyond the level of the effective transport coefficients and make a direct comparison between calculated and measured large-scale spatial deviations. The process of drying is of interest to a very wide range of engineering and scientific practitioners who are concerned with moisture transport in final or intermediate products. Some of these applications are given as follows: in agricultural products, paints and inks, wood, gels, soils, catalyst pellets, and foams. This investigation should permit a greater understanding of this important transport process.

该建议提出了一个理论和实验方案， 致力于干燥的预测理论的工作。 的 局部不均匀性的影响被纳入到这两个 理论框架和实验测量， 提出了 理论分析是基于 大规模的平均和封闭计划，其中包括 局部异质性的影响。 实验研究使 使用核磁共振成像（NMRI）来量化 多孔介质中的非均匀性和测量局部体积 干燥期间的平均饱和度。 空间的确定 局部体积平均饱和度的变化将 大尺度空间偏差的实验值 饱和度 这些反过来，将与预测从 关闭计算。 大规模平均法的主要特点是 速度出现大规模空间偏差， 浓度，并存在一个封闭的计划，可以预测 这些空间偏差。 在之前所有关于交通的研究中 现象，理论和实验进行了比较， 测量和预测的有效传输系数。 随着NMRI的使用，PI能够开发 有效输运系数水平以外的比较 并将计算值与实测值进行直接比较 大规模的空间偏差。 干燥的过程很有趣 广泛的工程和科学实践者， 与最终或中间阶段的水分输送有关 产品. 其中一些应用如下： 农产品、油漆和油墨、木材、凝胶、土壤、催化剂 颗粒和泡沫。 这项调查应该允许更大的 了解这一重要的运输过程。