Coupled heat and moisture transfer in diatomite-based humidity control material

doi:10.3969/j.issn.0438-1157.2014.09.007

Abstract

Abstract: A 1-D mathematical model is established for diatomite-based humidity control materials (DBHCM), to simulate the coupled heat and moisture migration process at different porosities, different ambient temperatures and different ambient relative humidities. The humidity control performance of DBHCM is tested and surfaces of DBHCM are characterized by micrograph. The results show that with the decrease of porosity, the amounts of adsorption and desorption increase, ambient temperature does not significantly influence the coupled heat and moisture migration process, and the effect of ambient temperature (the maximum deviation is 20℃) on the adsorption and desorption of DBHCM is about 10%. Better humidity control performance demands smaller pore diameter and larger quantity of small pores. The experimental results and the predictions of humidity control performance of DBHCM, as well as the micrograph representation of pore structures of DBHCM agree well with each others, which can fully verify the rationality of the mathematical model.

Key words: diatomite-based humidity control material, heat and moisture migration, pore structure, performance of humidity control

摘要： 建立了硅藻土基调湿材料内部热湿耦合迁移一维数学模型，模拟了不同孔隙率、不同环境温度和相对湿度下硅藻土基调湿材料中的热湿耦合迁移过程，结合硅藻土基调湿材料调湿性能实验测试结果以及硅藻土基调湿材料表面的显微图像分析，研究结果表明：随着孔隙率的减小，硅藻土基调湿材料的吸、放湿量均增大；环境温度对硅藻土基调湿材料热湿耦合迁移过程影响不显著，不同的环境温度（最大相差20℃）对硅藻土基调湿材料吸、放湿量的影响均在10%左右；硅藻土基调湿材料的孔径尺寸越小、小孔径孔隙数量越多，其调湿性能越好；硅藻土基调湿材料调湿性能的实测数据、模拟结果以及图像表征吻合良好，从而验证了理论模型的合理性。

关键词: 硅藻土基调湿材料, 热湿迁移, 孔隙结构, 调湿性能

CLC Number:

TU599

ZHENG Jiayi, CHEN Zhenqian. Coupled heat and moisture transfer in diatomite-based humidity control material[J]. CIESC Journal, 2014, 65(9): 3357-3365.

郑佳宜, 陈振乾. 硅藻土基调湿材料中热湿耦合传递[J]. 化工学报, 2014, 65(9): 3357-3365.

References 24

[1]	Tanaka, Miyano Saito. The variance of humidity in room according to wall materials//Research Report of Architectural Institute of Japan [R]. Fukuoka: Shukosha Printing Co., Ltd., 1949: 21-25
[2]	Maddison M, Mauring T, Kirsimäe K, et al. The humidity buffer capacity of clay-sand plaster filled with phytomass from treatment wetlands [J]. Build. Environ., 2009, 44 (9): 1864-1868
[3]	Horikawa T, Kitakaze Y, Sekida T, et al. Characteristics and humidity control capacity of activated carbon from bamboo [J]. Bioresour. Technol., 2010, 101 (11): 3964-3969
[4]	Hasegawa T, Iwasaki S, Shibutani Y, et al. Preparation of superior humidity-control materials from Kenaf [J]. J. Porous Mat., 2009, 16 (2): 129-134
[5]	Vu D H, Wang K S, Bac B H. Humidity control porous ceramics prepared from waste and porous materials [J]. Mater. Lett., 2011, 65 (6): 940-943
[6]	Vu D H, Wang K S, Bac B H, et al. Humidity control materials prepared from diatomite and volcanic ash [J]. Constr. Build. Mater., 2013, 38: 1066-1072
[7]	Watanabe O, Ishida E H, Maeda H. Development of an autonomous humidity controlling building material by using mesopores [J]. Transactions of the Materials Research Society of Japan, 2008, 33 (2): 489-492
[8]	Wang R M, Wang J F, Wang X W, et al. Preparation of acrylate-based copolymer emulsion and its humidity controlling mechanism in interior wall coatings [J]. Prog. Org. Coat., 2011, 71 (4): 369-375
[9]	Djongyang N, Tchinda R, Njomo D. A study of coupled heat and mass transfer across a porous building component in intertropical conditions [J]. Energy Build., 2009, 41 (5): 461-469
[10]	Talukdar P, Olutmayin S O, Osanyintola O F, et al. An experimental data set for benchmarking 1-D, transient heat and moisture transfer models of hygroscopic building materials (Ⅰ): Experimental facility and material property data [J]. Int. J. Heat Mass Transf., 2007, 50 (23): 4527-4539
[11]	Talukdar P, Osanyintola O F, Olutmayin S O, et al. An experimental data set for benchmarking 1-D, transient heatand moisture transfer models of hygroscopic building materials (Ⅱ): Experimental, numerical and analytical data [J]. Int. J. Heat Mass Transf., 2007, 50 (23): 4915-4926
[12]	Abahri K, Belarbi R, Trabelsi A. Contribution to analytical and numerical study of combined heat and moisture transfers in porous building materials [J]. Build. Environ., 2011, 46 (7): 1354-1360
[13]	Luikov A V. Heat and Mass Transfer in Capillary-porous Bodies [M]. Oxford: Pergamon Press, 1966
[14]	Osanyintola O F, Talukdar P, Simonson C J. Effect of initial conditions, boundary conditions and thickness on the moisture buffering capacity of spruce plywood[J]. Energy Build., 2006, 38 (10): 1283-1292
[15]	Ceaglske N H, Hougen O A. Drying granular solids [J]. Industrial & Engineering Chemistry, 1937, 29 (7): 805-813
[16]	de Vries D A. The theory of heat and moisture transfer in porous media revisited [J]. Int. J. Heat Mass Transf., 1987, 30 (7): 1343-1350
[17]	Henry P S H. Diffusion in absorbing media [J]. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1939, 171 (945): 215-241
[18]	Luikov A V. Capillary-porous bodies [J]. Advanc. Heat Transfer, 1964, 1: 173-184
[19]	Luikov A V, Shashkov A G, Vasiliev L L, et al. Thermal conductivity of porous systems [J]. Int. J. Heat Mass Transf., 1968, 11 (2): 117-140
[20]	Luikov A V. Systems of differential equations of heat and mass transfer in capillary-porous bodies (review) [J]. Int. J. Heat Mass Transf., 1975, 18 (1): 1-14
[21]	Whitaker S. The transport equations for multi-phase systems [J]. Chem. Eng. Sci., 1973, 28 (1): 139-147
[22]	Luikov A V. Theory Basis of Building Thermal Physics [M]. Beijing: Science Press, 1965
[23]	Chen Zhaoyi (陈昭宜), Liu Ruimei (刘蕊梅). A new calculation formula of gas diffusion coefficient [J]. Chinese Science Bulletin (科学通报), 1989, 11: 029
[24]	Zhang Yinping (张寅平), Zhang Lizhi (张立志), Liu Xiaohua (刘晓华). Mass Transfer in Built Environment (建筑环境传质学) [M]. Beijing: Chinese Architectural Press, 2006