Hunting for the perfect phase change material (PCM) for the built environment

英国近50%的碳排放来自建筑环境，其中大部分是低能效建筑的供暖和制冷的结果。气候变化趋势预测，英国境内的温度将上升，这将在适当的时候导致能源消耗的上升，以保持室内热舒适度。相变材料，也称为（PCM）是在相变期间存储和释放高热能的物质。当被纳入建筑环境中时，PCM提供了巨大的希望，因为它们可以减少碳排放和能源账单，沿着改善建筑物居住者的热舒适度。这个博士项目的目的是寻找或开发具有成本效益和可持续性的PCM，作为气候变化对建筑环境影响的潜在解决方案。作为本博士的初步阶段，将对现有的建筑环境PCM及其局限性进行文献综述。这将导致提出可能的解决方案，其中一些是本博士计划解决的问题。在过去，大多数与PCM在建筑环境中的使用相关的研究都是针对固-液PCM进行的。因此，本研究项目将对固-液和固-固相变材料进行研究，重点是固-固相变材料。潜在的相变材料，如六水氯化钙，十水硫酸钠，聚乙二醇（PEG），PureTemp 24 X，X25，X30，X40，X55和X70将经历几个研究阶段。第一阶段是筛选阶段，将研究PCM的一些关键性能，例如：潜热能，熔点/转变点，热导率，成本和安全性。新型PCM的安全性可以通过测量其对活生物体（如细菌和藻类）的影响来量化，然而，对于已知的PCM，将使用可靠的文献来源来确定其安全性。在第二阶段中，发现具有适当相变温度（约100 ° C）的任何PCM都可以在第二阶段中被加热。18 - 30 ℃）、高潜热能、高熔点、高导热性、低环境和健康风险，并且是广泛可用的;将被结合到不同的建筑材料中（例如，混凝土、砖、石膏和石膏板）及其复合材料将进行耐久性测试、热循环、DSC、TGA和SEM等测试。在最后阶段，将对PCM复合材料进行生命周期分析和节能性能等研究。对于相变温度高于预期范围（18 - 30 ℃）的PCM，将对其物理化学性能进行修改。在化学中，改变材料的物理化学性质被称为调谐。有许多方法可以调整材料的特性，然而，最常见的方法是将杂质（杂质或添加剂）引入纯材料。重要的是要注意，使用的任何潜在添加剂必须具有在分子水平上与PCM相互作用的能力。因此，添加剂必须具有共同的官能团（在有机PCM的情况下）或共同的阳离子或阴离子（在无机PCM的情况下）。这将确保添加剂将干扰PCM分子之间的分子间相互作用并最终改变其相变温度。这个博士项目将涵盖的另一个方面是创建一个数据库，其中包括所有可能被纳入建筑环境的潜在PCM，重点是生物基PCM。

Almost 50% of the UK total carbon emissions come from the built environment, much of which is an outcome of heating and cooling of low energy-efficient buildings. The climate change trends predict an increase in temperatures within the UK, which in due course will lead to a rise in energy consumption to maintain indoor thermal comfort. Phase change materials, also known as (PCMs) are substances that store and release high thermal energy during phase transition. When incorporated into the built environment, PCMs offer tremendous promise as they can reduce carbon emissions and energy bills, along with improve thermal comfort for occupants of buildings. The purpose of this PhD project is to find or develop cost-effective and sustainable PCM as a potential solution to the impact of climate change on the built environment. As preliminary phase of this PhD, a literature review will be conducted on existing PCM for the built environment and their limitations. This will lead to proposing possible solutions of which some of them are the ones that this PhD is planning to address. In the past, most research related to the use of PCMs in the built environment has been done for solid-liquid PCMs. Therefore, in this research project both solid-liquid and solid-solid PCMs will be studied with emphasis on solid-solid PCMs.Potential PCMs such as calcium chloride hexahydrate, sodium sulphate decahydrate, polyethylene glycol (PEG), PureTemp 24X, X25, X30, X40, X55 and X70 will undergo several investigation stages. The first stage is the screening stage, where some of the key properties such as: latent heat energy, melting/transition point, thermal conductivity, costs, and safety of the PCM will be studied. The safety of novel PCMs can be quantified by measuring their effect on living organisms such as bacteria and algae, however, for known PCMs reliable literature sources will be used to determine their safety. In the second stage, any PCMs found to have the appropriate phase change temperature (Approx. 18 - 30 C), high latent heat energy, high melting point, high thermal conductivity, low environmental & health risks, and are widely available; would be incorporated into different building materials (e.g., concrete, bricks, plaster, and gypsum boards) and their composites will undergo tests like durability tests, thermal cycling, DSC, TGA, and SEM.In the final stage, other studies such as Life Cycle Analysis and energy-saving performance will be conducted on the PCM composites.For PCMs that have a higher phase transition temperature than the desired range (18 - 30 C), their physicochemical properties will be modified. In chemistry modifying the physicochemical properties of a material is called Tuning. There are many ways of tuning the properties of a material, however, the most common method is the introduction of foreign substances (impurities or additives) to the pure material. It is important to note that any potential additives used; must have the ability to interact with the PCMs at a molecular level. Therefore, additives must either have a common functional group (In the case of organic PCMs) or a common cation or anion (In the case of inorganic PCMs). This will ensure that the additive will disturb the intermolecular interaction between the PCM's molecules and ultimately alter its phase change temperature. Another aspect this PhD project will cover is creating a database that includes all the potential PCMs which could be incorporated into the built environment with emphasis on biobased PCMs.