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Rheological aspects and thermal behaviors of extruded panels.

机译：挤塑板的流变特性和热行为。

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摘要

Developing thermal energy-storing building materials is one of the effective ways to solve global energy and environmental problems we face. Incorporations of phase change materials (PCM) in building materials have been proved to be feasible to exploit high thermal storage capability of PCM to achieve the objective. In this study, short fiber reinforced cementitious panels incorporated with granular phase change composites have been manufactured by the extrusion technique which can significantly improve the mechanical performance of cement composites. In order to make extrusion process smooth and successful, rheological behaviors of fresh fiber reinforced cementitious composites need to be examined carefully.;Firstly, rheological behaviors of fresh extrudate were investigated by utilizing upsetting or squeeze flow test throughout present study. Then a model containing both strain and strain rate was proposed to represent the stress strain relationships of fresh extrudate under different strain rates. The friction conditions were studied and friction factor was derived by using upper bound theory. Material parameters in the model were determined from experimental data. After that, the model was validated through Finite Element Method. Reasonable agreement between simulations and experimental results was achieved. Theoretical analysis of upsetting was further carried out in the interest of understanding the upsetting process better. A simple expression for the total force required to compress the specimen was developed. Agreement between this expression and experimentally measured force was good at strain values higher than elastic. In order to improve accuracy, an inverse problem was formulated with genetic algorithm to search accurate value of the parameters. During investigations process of rheological behaviors, digital image processing (DIP) technique was also used. Dimensions of deformed specimens which could provide useful information related to friction conditions were measured. And the displacements both at edges and contacting surface of specimen undergoing deformation were measured. Time dependent behaviors of fresh extrudate caused by chemical reactions and extrudability were assessed by stress relaxation and upsetting tests. A data interpretation method and generalized Maxwell model were used to interpret the stress relaxation process. At the same time, the influences of rheology modifier were addressed.;Secondly, productions of granular phase change composites and thermal energy-storing panels were presented. The thermal behaviors of extruded panels were investigated by one-dimensional heat conduction and simulated-room tests. It was shown that both heat capacity and thermal inertia were largely improved. The experimental results demonstrated that there could be a great potential for applying extruded thermal energy-storing panels in building constructions to improve energy efficiency.
机译：开发热能存储建筑材料是解决我们面临的全球能源和环境问题的有效方法之一。已经证明在建筑材料中掺入相变材料（PCM）对于利用PCM的高储热能力来实现该目标是可行的。在这项研究中，通过挤出技术制造了掺入颗粒状相变复合材料的短纤维增强水泥板，可以显着改善水泥复合材料的机械性能。为了使挤出过程顺利和成功，需要仔细检查新鲜纤维增强水泥基复合材料的流变行为。首先，在整个研究过程中，通过up锻或挤压流动试验研究了新鲜挤出物的流变行为。然后提出了同时包含应变和应变率的模型，以表示在不同应变率下新鲜挤出物的应力应变关系。研究了摩擦条件，并运用上限理论推导了摩擦系数。根据实验数据确定模型中的材料参数。之后，通过有限元方法对模型进行了验证。模拟与实验结果之间取得了合理的一致性。为了更好地了解the锻过程，对up锻进行了理论分析。建立了压缩样品所需总力的简单表达式。在高于弹性值的应变值下，此表达式与实验测得的力之间的一致性很好。为了提高精度，利用遗传算法提出了一个反问题，以求出准确的参数值。在流变行为的调查过程中，还使用了数字图像处理（DIP）技术。测量了可提供与摩擦条件有关的有用信息的变形试样的尺寸。并测量了试样在变形时的边缘和接触面的位移。由化学反应和可挤出性引起的新鲜挤出物随时间变化的行为通过应力松弛和up锻测试进行评估。数据解释方法和广义麦克斯韦模型被用来解释应力松弛过程。同时，研究了流变改性剂的影响。其次，介绍了颗粒相变复合材料和储热板的生产。通过一维热传导和模拟室测试研究了挤塑板的热行为。结果表明，热容量和热惯性都大大提高了。实验结果表明，在建筑结构中应用挤压热能存储板以提高能源效率具有巨大的潜力。

著录项

  • 作者

    Li, Xiangyu.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 298 p.
  • 总页数 298
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;
  • 关键词

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