Investigation of thermo-mechanical performance of PCM incorporated Geothermal Energy Pile (PCMinGEEP)

PCM 地热能桩 (PCMinGEEP) 的热机械性能研究

• 批准号: EP/S037349/1
• 负责人: Rao Martand Singh
• 金额: $ 27.31万
• 依托单位: University of Surrey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FS037349%2F1
• 关键词: Investigation; thermo; mechanical; performance; PCM

The latest report of Intergovernmental Panel on Climate Change (IPCC) 'Global warming of 1.5C' emphasises the need for 'rapid and far-reaching' actions now to curb carbon emission to limit global warming and climate change impact. Decarbonising heating is one of the actions which is going to play a key role in reducing carbon emission. The Committee on Climate Change states that insufficient progress has been made towards the low carbon heating homes target that requires immediate attention to meet our carbon budget.It is well known fact that the ground is warmer compared to air in winter and cooler in summer. Therefore our ancestors build caves and homes underground to protect them against extreme cold/hot weather. Geothermal energy pile (GEEP) basically consists of a pile foundation, heat exchanging loops and a heat pump. Heat exchanging loops are usually made of high density polyethylene pipes and carry heat exchanging fluid (water and/or ethylene glycol). Loops are attached to a reinforcement cage and installed into the concrete pile foundations of a building to extract the shallow ground energy via a heat pump to heat the building during winter. The cycle is reversed during summer when heat is collected from the building and stored in the ground. GEEP can play an important role in decarbonising heating as it utilises the sustainable ground energy available under our feet.High initial cost remains the main challenge in deploying heat pump technology. In the case of GEEP, the initial cost can be reduced, if the heat capacity of the concrete is improved and loop length can thus be decreased. This can be achieved by incorporating phase change material (PCM) in the concrete. PCM has a peculiar characteristic that it absorbs or releases large amount of energy during phase change (solid to liquid or liquid to solid). This project aims to develop an innovative solution by combining two technologies GEEP and PCM to obtain more heat energy per unit loop length which would reduce the cost of GEEP significantly. PCM has never been used with GEEP in the past, therefore obvious research questions that come to the mind are (1) how to inject PCM in concrete (2) what would be the effect of PCM on concrete strength and workability (3) how PCM would affect load capacity of GEEP as primary objective of the GEEP is to support structure (4) how much heat energy would be available (5) what would happen to the ground temperature surrounding GEEP (6) how much it would cost (7) whether it would reduce carbon footprint of concrete. We aim to answer all the above research questions by employing sustainable and environmental friendly PCM and impregnate it in light weight aggregates (LWAs) made with waste material (e.g. fly ash, slag, glass). There are three advantages of using LWAs made from waste: first LWAs will replace natural aggregate in concrete as natural aggregates are carbon intense, second LWAs are porous and light so they can absorb large amount of PCM and reduce the weight of concrete, third reuse the waste. Laboratory scale concrete GEEP will be made with PCM impregnated LWAs and tested under heating and cooling load to investigate thermal (heat transfer) and mechanical (load capacity) performance. Extensive experimental and numerical study will be carried out to design and develop novel PCM incorporated GEEP which can provide renewable ground energy for heating and cooling.

政府间气候变化专门委员会(IPCC)的最新报告《全球变暖1.5摄氏度》强调，现在有必要采取快速而深远的行动来遏制碳排放，以限制全球变暖和气候变化的影响。除碳加热是其中一项行动，它将在减少碳排放方面发挥关键作用。气候变化委员会表示，在实现低碳供暖住宅目标方面进展不足，需要立即关注以满足我们的碳预算。众所周知，与空气相比，地面在冬季更温暖，在夏季更凉爽。因此，我们的祖先在地下建造洞穴和住所，以保护他们免受极端寒冷/炎热天气的侵袭。地热能桩主要由桩基础、换热回路和热泵组成。换热回路通常由高密度聚乙烯管制成，并携带换热流体(水和/或乙二醇)。环路安装在钢筋笼上，安装在建筑物的混凝土桩基上，通过热泵提取浅层地面能量，在冬季为建筑物供暖。在夏季，当热量从建筑物收集并储存在地面上时，这种循环是相反的。GEEP可以在减少供暖方面发挥重要作用，因为它利用了我们脚下可用的可持续地面能源。高昂的初始成本仍然是部署热泵技术的主要挑战。在GEEP的情况下，如果提高混凝土的热容量，从而减少环路长度，可以降低初始成本。这可以通过在混凝土中加入相变材料(PCM)来实现。相变材料具有一个独特的特性，它在相变(固-液或液-固)过程中吸收或释放大量的能量。本项目旨在开发一种创新的解决方案，将GEEP和PCM两种技术相结合，以获得更多的单位环长热能，从而显着降低GEEP的成本。PCM在过去从未与GEP一起使用过，因此脑海中浮现出明显的研究问题：(1)如何在混凝土中注入PCM(2)PCM将对混凝土强度和工作性产生什么影响(3)PCM将如何影响GEP的承载能力，因为GEP的主要目标是支撑结构(4)将有多少热能可用(5)GEP周围的地面温度将发生什么变化(6)它将花费多少(7)它是否会减少混凝土的碳足迹。我们的目标是通过采用可持续和环保的相变材料来回答所有上述研究问题，并将其浸泡在由废物(如飞灰、矿渣、玻璃)制成的轻质骨料中。利用废渣制取混凝土有三个优点：一是由于天然骨料碳密集，可以取代天然骨料用于混凝土；二是多孔轻质，可以吸收大量的PCM，减轻混凝土重量；三是回收利用废渣。实验室规模的混凝土土工布将用PCM浸渍的LIS制成，并在热负荷和冷负荷下进行测试，以研究热(传热)和力学(承载能力)性能。将开展大量的实验和数值研究，以设计和开发新型的PCM，包括GEEP，它可以为供暖和制冷提供可再生的地面能源。

项目成果

Assessment of impregnating phase change materials into lightweight aggregates for development of thermal energy storage aggregate composites

• DOI: 10.1016/j.conbuildmat.2021.124683
• 发表时间: 2021-09-04
• 期刊: CONSTRUCTION AND BUILDING MATERIALS
• 影响因子: 7.4
• 作者: Sani, Abubakar Kawuwa;Olawoore, Isaac Olaniyi;Singh, Rao Martand
• 通讯作者: Singh, Rao Martand

Numerical investigation of the performance of geothermal energy piles under different soil moisture conditions

不同土壤湿度条件下地热能桩性能的数值研究

• DOI: 10.5194/egusphere-egu2020-20003
• 发表时间: 2020
• 作者: Sani A

Long-Term Thermal Performance of Group of Energy Piles in Unsaturated Soils under Cyclic Thermal Loading

• DOI: 10.3390/en14144122
• 发表时间: 2021-07
• 期刊: Energies
• 影响因子: 3.2
• 作者: A. Sani;R. Singh

Numerical investigation of the performance of group of geothermal energy piles in unsaturated sand

• DOI: 10.1051/e3sconf/202020505025
• 发表时间: 2020
• 期刊: E3S Web of Conferences
• 作者: A. Sani;R. Singh