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气体稀薄及扩散效应对气凝胶隔热材料传热的影响研究

发表时间:2018-07-31  浏览量:926  下载量:184
全部作者: 唐桂华,卢银彬,毕成,郭江峰,刘蔚,马原
作者单位: 西安交通大学能源与动力工程学院;西安特种设备检验检测院
摘 要: 纳米多孔气凝胶广泛应用于隔热领域,针对气凝胶隔热材料中的气体稀薄及扩散效应问题,通过在非稳态传热方程中添加源项法研究孔隙中气体稀薄扩散效应对多孔隔热材料非稳态传热的影响,数值模拟研究了渗透率(材料绝对渗透率和稀薄气体在材料中的表观渗透率)对非稳态传热的影响,建立利用渗透率预测的多孔隔热材料背温关联式。研究结果表明,气体在高渗透率材料孔隙中能更加自由地传递,提高材料背温,最终恶化材料隔热性能。密度较大的材料对应较小的渗透率,限制了气体在多孔材料中的扩散,对提高材料的隔热性能具有积极作用。工程上应选用大密度、低渗透率的多孔材料作为保温隔热材料。研究成果为纳米多孔隔热材料的工程优化设计提供了理论指导。
关 键 词: 工程热物理;稀薄扩散效应;非稳态传热;克努森数
Title: Effects of gas rarefaction and diffusion effect on transient heat transfer of aerogel insulation material
Author: TANG Guihua, LU Yinbin, BI Cheng, GUO Jiangfeng, LIU Wei, MA Yuan
Organization: School of Energy and Power Engineering, Xi'an Jiaotong University; Xi'an Special Equipment Inspection Institute
Abstract: Nano-porous aerogel materials have been used widely in high temperature insulation field. In the view of the problems of gas rarefaction and diffusion effect of aerogel insulation material, the influences of gas diffusion and rarefaction effect on transient heat transfer performance of nano-porous insulation materials are numerically studied by adding a source term in transient heat conduction equation. Effects of intrinsic permeability and gas apparent permeability on transient heat conduction are investigated by numerical simulation. A model relating the permeability is established to predict the back temperature of porous insulation media. Gas moves faster in materials with large permeability which causes the back temperature increase and makes heat insulation performance of materials worse. In addition, large-density materials with low permeability decrease the velocity of gas diffusion, and have a positive role for improving heat insulation performance. Nano-porous aerogel insulation materials with large density and low permeability can be employed in engineering. The present study provides guidance for project optimization design of nano-porous insulation materials.
Key words: engineering thermophysics; rarefaction diffusion effect; transient heat transfer; Knudsen number
发表期数: 2018年7月第14期
引用格式: 唐桂华,卢银彬,毕成,等. 气体稀薄及扩散效应对气凝胶隔热材料传热的影响研究[J]. 中国科技论文在线精品论文,2018,11(14):1468-1475.
 
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