{"title":"基于双扩散模型的填料床流体流动及热湿传递机理模拟","authors":"Xin Li, Kaimin Yang, Yuancheng Wang, Xinming Du","doi":"10.1080/00986445.2023.2272183","DOIUrl":null,"url":null,"abstract":"AbstractBased on the discrete element method (DEM), four packed beds composed of soybean kernels with diameters of 6.4, 6.8, 7.4 mm, and the mixture of three kinds of particles were established. Then, a double-diffusion heat and mass transfer model between the grain pile and the interstitial air was established based on the local mass and thermal non-equilibrium (LMTNE) mechanism. Finally, employing particle-resolved computational fluid dynamics (PRCFD), the heat and mass transfer between the grain kernels and air during the drying process in the four packed beds were numerically resolved. It was found that the packed bed formed by stacking particles of different diameters had a minimum porosity of 0.4547. The radial porosity of the packed bed oscillates and decreases toward the central axis, while the tortuosity of the airflow path oscillates and decays toward the periphery. The mass transfer Biot number for soybean kernels with diameters of 6.4, 6.8, and 7.4 mm were 2.38 × 106, 2.44 × 106, and 2.53 × 106, respectively. This indicates that the mass transfer rate in the grain pile primarily depends on the magnitude of the moisture diffusion coefficient within the grain kernels. Compared with mass diffusion, thermal diffusion occurs much faster, which results in temperature gradients in packed beds only existing in the first 5 min of drying, and the drying rate in the early stage is higher than that in the later stage. Most importantly, the airflow characteristics, heat and moisture content are not in local equilibrium in the packed bed, and should be considered when designing drying systems.Keywords: Biot numberdouble-diffusionheat-moisture coupling transferporositysoybeantortuosity Disclosure statementThe authors declare that they have no conflicts of interest.Additional informationFundingThis study was supported by the Scientific and Technological Innovation Project for Youth of Shandong Provincial Colleges and Universities (Grant No. 2019KJH012). The Plan of Guidance and Cultivation for Young Innovative Talents of Shandong Provincial Colleges and Universities.","PeriodicalId":9725,"journal":{"name":"Chemical Engineering Communications","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Simulation of fluid flow and heat-moisture transfer mechanism in packed bed based on double-diffusion model\",\"authors\":\"Xin Li, Kaimin Yang, Yuancheng Wang, Xinming Du\",\"doi\":\"10.1080/00986445.2023.2272183\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"AbstractBased on the discrete element method (DEM), four packed beds composed of soybean kernels with diameters of 6.4, 6.8, 7.4 mm, and the mixture of three kinds of particles were established. Then, a double-diffusion heat and mass transfer model between the grain pile and the interstitial air was established based on the local mass and thermal non-equilibrium (LMTNE) mechanism. Finally, employing particle-resolved computational fluid dynamics (PRCFD), the heat and mass transfer between the grain kernels and air during the drying process in the four packed beds were numerically resolved. It was found that the packed bed formed by stacking particles of different diameters had a minimum porosity of 0.4547. The radial porosity of the packed bed oscillates and decreases toward the central axis, while the tortuosity of the airflow path oscillates and decays toward the periphery. The mass transfer Biot number for soybean kernels with diameters of 6.4, 6.8, and 7.4 mm were 2.38 × 106, 2.44 × 106, and 2.53 × 106, respectively. This indicates that the mass transfer rate in the grain pile primarily depends on the magnitude of the moisture diffusion coefficient within the grain kernels. Compared with mass diffusion, thermal diffusion occurs much faster, which results in temperature gradients in packed beds only existing in the first 5 min of drying, and the drying rate in the early stage is higher than that in the later stage. Most importantly, the airflow characteristics, heat and moisture content are not in local equilibrium in the packed bed, and should be considered when designing drying systems.Keywords: Biot numberdouble-diffusionheat-moisture coupling transferporositysoybeantortuosity Disclosure statementThe authors declare that they have no conflicts of interest.Additional informationFundingThis study was supported by the Scientific and Technological Innovation Project for Youth of Shandong Provincial Colleges and Universities (Grant No. 2019KJH012). The Plan of Guidance and Cultivation for Young Innovative Talents of Shandong Provincial Colleges and Universities.\",\"PeriodicalId\":9725,\"journal\":{\"name\":\"Chemical Engineering Communications\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.9000,\"publicationDate\":\"2023-10-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Chemical Engineering Communications\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1080/00986445.2023.2272183\",\"RegionNum\":4,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ENGINEERING, CHEMICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Engineering Communications","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1080/00986445.2023.2272183","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
Simulation of fluid flow and heat-moisture transfer mechanism in packed bed based on double-diffusion model
AbstractBased on the discrete element method (DEM), four packed beds composed of soybean kernels with diameters of 6.4, 6.8, 7.4 mm, and the mixture of three kinds of particles were established. Then, a double-diffusion heat and mass transfer model between the grain pile and the interstitial air was established based on the local mass and thermal non-equilibrium (LMTNE) mechanism. Finally, employing particle-resolved computational fluid dynamics (PRCFD), the heat and mass transfer between the grain kernels and air during the drying process in the four packed beds were numerically resolved. It was found that the packed bed formed by stacking particles of different diameters had a minimum porosity of 0.4547. The radial porosity of the packed bed oscillates and decreases toward the central axis, while the tortuosity of the airflow path oscillates and decays toward the periphery. The mass transfer Biot number for soybean kernels with diameters of 6.4, 6.8, and 7.4 mm were 2.38 × 106, 2.44 × 106, and 2.53 × 106, respectively. This indicates that the mass transfer rate in the grain pile primarily depends on the magnitude of the moisture diffusion coefficient within the grain kernels. Compared with mass diffusion, thermal diffusion occurs much faster, which results in temperature gradients in packed beds only existing in the first 5 min of drying, and the drying rate in the early stage is higher than that in the later stage. Most importantly, the airflow characteristics, heat and moisture content are not in local equilibrium in the packed bed, and should be considered when designing drying systems.Keywords: Biot numberdouble-diffusionheat-moisture coupling transferporositysoybeantortuosity Disclosure statementThe authors declare that they have no conflicts of interest.Additional informationFundingThis study was supported by the Scientific and Technological Innovation Project for Youth of Shandong Provincial Colleges and Universities (Grant No. 2019KJH012). The Plan of Guidance and Cultivation for Young Innovative Talents of Shandong Provincial Colleges and Universities.
期刊介绍:
Chemical Engineering Communications provides a forum for the publication of manuscripts reporting on results of both basic and applied research in all areas of chemical engineering. The journal''s audience includes researchers and practitioners in academia, industry, and government.
Chemical Engineering Communications publishes full-length research articles dealing with completed research projects on subjects such as experimentation (both techniques and data) and new theoretical models. Critical review papers reporting on the current state of the art in topical areas of chemical engineering are also welcome; submission of these is strongly encouraged.