Advancement in Solid-Liquid Heat Transfer and Latent Heat Energy Storage Applications

固液传热和潜热储能应用的进展

• 批准号: RGPIN-2014-06493
• 负责人: Groulx, Dominic
• 金额: $ 1.75万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612258
• 关键词: Advancement; Solid; Liquid; Heat; Transfer

Solid-liquid phase change processes are encountered in a wide variety of fields including: energy, environmental, material processing and microelectronics. They are found in such applications as: latent heat energy storage systems (LHESS), temperature control and management. LHESS are used to store thermal energy through the melting of phase change materials (PCMs); this energy can be recuperated when the PCMs solidifies. This enables the temporal decoupling of thermal energy input and output useful for renewable (solar, wind) or waste heat applications for example. Also, through this phase change process significantly more thermal energy can be stored in PCMs compared to sensible heating of a substance like water. However, PCMs have very low thermal conductivities which can make storing or retrieving thermal energy from them a lengthy process unless proper design and control strategies are applied to enhance the apparent thermal conductivity or optimize the heat exchange process. Study of these systems involves research in heat transfer and fluid mechanics; and it has been shown by the applicant and others that both conduction and natural convection play a significant role in the overall phase change behaviour inside LHESS. However, most existing literature on the subject presents studies where only one heat transfer mode is considered, typically conduction, which places a complete understanding of the coupled processes still out of reach. Optimization and thermal enhancement of LHESS requires a complete understanding of the impact of natural convection and the melting/solidification heat transfer processes within the systems. To address these research deficiencies, the objectives of this research program are to: 1) study the fundamentals of solid-liquid phase change heat transfer to further the understanding of the impact of natural convection in the liquid melt on the overall phase change process in various system geometries and using various PCMs; 2) design and optimize LHESS for thermal storage for renewable energy and waste heat applications to counteract the low thermal conductivity of PCM and test under real-time solar thermal operations. Outcomes from this research will be a detailed and accurate understanding of natural convection during melting and strategies to enhance heat transfer during every mode of operation of LHESS (charging, discharging, simultaneous). Experimental results will serve to validate numerical models of phase change heat transfer prepared on commercial software used to facilitate the early adoption of the models by practicing engineers. Finally, a methodology to design the heat exchangers found inside LHESS to optimize their operation, and energy input and output rates as a function of the storage application will be developed. This is an important experimental and theoretical research area because proper understanding of these processes, and their application to energy and thermal systems, will facilitate the management of energy demand, use and production. For example, LHESS can be used to store thermal energy during off-peak electricity demand periods, reducing the amount of electricity produced to meet the demand during peak periods. Similar storage systems can be used to store solar energy in order to use it later in the day when the sun is down. As another example, small amounts of PCM can be incorporated into electronic devices to manage and delay temperature increase during intermittent operations. Our country, along with the rest of the world, will face an energy crisis in the decades to come. In that context, research in the area of thermal/energy engineering has the potential to lead to the development of new and vital energy technologies for Canada.

在各种领域中遇到固液相变过程，包括：能量，环境，材料加工和微电子学。它们在以下应用中找到：潜热储能系统（LHES），温度控制和管理。 LHESS用于通过相变材料（PCM）的熔化来存储热能；当PCM巩固时，可以将这种能量恢复。这使热能输入和输出的时间脱钩可用于可再生（太阳能，风）或废热应用。同样，与对水（如水）的明智加热相比，通过这种相变的过程可以在PCM中储存更多的热能。但是，除非采用适当的设计和控制策略来增强明显的导热率或优化热交换过程，否则PCM具有非常低的导热率，可以使其从中储存或从中获取热能。 对这些系统的研究涉及传热和流体力学的研究。申请人和其他人都表明，传导和自然对流在LHESS内部的整体相变行为中起着重要作用。但是，关于该主题的大多数现有文献都介绍了研究，其中仅考虑一种传热模式，通常是传导，这使人们完全了解仍然无法触及的耦合过程。 LHESS的优化和热增强需要完全了解系统内自然对流的影响以及熔化/固化的传热过程。 为了解决这些研究缺陷，该研究计划的目标是： 1）研究固定相变热传热的基本原理，以进一步了解液体中自然对流对各种系统几何形状和使用各种PCM的整体相变过程的影响； 2）设计并优化用于热存储的LHES，以供可再生能源和废热应用，以抵消PCM的低导热率，并在实时太阳能热操作下进行测试。 这项研究的结果将是对在LHESS（充电，放电，同时）进行融化和策略期间自然对流的详细而准确的理解。实验结果将有助于验证基于用于促进工程师早期采用模型的商业软件制备的相变热传播的数值模型。最后，将开发一种设计在LHES中发现的热交换器以优化其操作的方法，并将开发能量输入和输出速率作为存储应用程序的函数。 这是一个重要的实验和理论研究领域，因为对这些过程的适当了解及其在能源和热系统中的应用将有助于对能源需求，使用和生产的管理。例如，LHES可用于在非高峰电力需求期间存储热能，从而减少了满足高峰期需求的电力量。类似的存储系统可用于存储太阳能，以便在太阳下降的那天晚些时候使用它。作为另一个例子，可以将少量PCM纳入电子设备中，以管理和延迟间歇性操作期间的温度升高。我们的国家以及世界其他地区将在未来几十年中面临能源危机。在这种情况下，热/能源工程领域的研究有可能导致加拿大新的和重要的能源技术的发展。