有机相变材料应用的研究进展

介绍了有机相变材料的性能和特点,综述了部分新型有机相变材料的制备技术进展,阐述了有机相变材料在建筑节能、军事伪装领域的应用研究进展,提出了其在军事伪装领域应用的技术难题及克服难题可能的方法,并展望了有机相变材料在上述两方面的应用前景.     

与建筑一体化脂肪酸类相变材料的研究及应用

脂肪酸类相变材料具有良好的热物理性能、热稳定性和化学稳定性,是一类储热性能优良、易于与建筑形成一体化的有机相变材料,通过与传统的建筑材料复合可有效降低建筑能耗,起到建筑节能和调整建筑室内环境舒适度的作用。综述了脂肪酸类相变材料的研究进展及其在建筑中的主要应用情况,并对目前脂肪酸类相变材料在建筑中应用所存在的问题进行了总结。最后对其进一步的发展做了分析和展望。     

相变蓄热材料在节能建筑领域的应用与研究进展

相变蓄热材料是一种能够储存热能的新型化学材料,通过在特定温度下吸收或放出热量发生物相变化,实现热量的储存与释放。根据化学成分不同将相变蓄热材料分为无机、有机和复合类相变材料,由于存储密度高、热容大和热稳定性较好等优点,相变蓄热材料已在一定范围内应用于建筑节能领域。介绍了相变材料的种类、特性以及蓄能机理,分类归纳了相变蓄热材料在建筑物围护结构和建筑物中制冷供暖系统中的应用,包括蓄能墙体、蓄能地板、蓄能屋顶、相变蓄热集热器、相变热泵供暖系统、相变制冷系统、相变冷却吊顶等。并结合目前研究现状分析了相变蓄热材料在研制和应用过程中存在的一些问题,最后,展望了相变蓄热材料在建筑领域的发展方向和应用前景。     

复合相变蓄热材料研究进展

相变材料是目前热门的功能材料,在储存和释放能量的过程中,温度保持不变或稳定在一定的温度区间内,使得相变材料不仅能实现热量储存且具有温度调控功能。复合相变材料由于具有多种单一材料的性质而成为研究热点,并广泛应用在建筑节能、电子器件热管理等方面。本文分类归纳了相变材料的特征,并根据化学成分不同将复合相变蓄热材料分为有机-有机、无机-无机和有机-无机三大类,结合研究现状分类梳理了不同类型复合相变蓄热材料的优缺点,并对其蓄热特性进行归纳对比。总结了复合相变蓄热材料的应用现状,结合能源应用现状和环境情况进一步分析了今后的研究和发展方向,认为未来的复合相变材料应该是高效蓄热、灵敏准确、价格低廉、环保可降解的新型复合相变材料。     

浅谈相变材料在建筑中的应用

相变材料的应用是实现建筑节能的有效措施。阐述相变材料应用于建筑中的条件,介绍相变材料与普通建材结合的方法,剖析相变建材的应用研究现状,并对相变材料在建筑中应用的前景进行分析。     

有机相变蓄冷材料的研究进展

本文概述了有机相变蓄冷材料和有机-无机复合相变蓄冷材料的研究进展,探讨了采用公式指导低共融物相变蓄冷材料配比和提高有机相变材料导热能力的方法,介绍了相变材料在太阳能利用、电力的峰谷平衡、空调节能与冷藏运输等方面的应用研究。指出相变材料的性能特性、相变机理、传热理论模型及复合技术是有机相变蓄冷材料研究的重点内容,有机复合相变蓄冷材料是今后有机相变材料的重点发展方向。     

相变材料在建筑节能中的研究及应用

相变材料是一类高效的储能物质,通过与传统的建筑材料复合可提升建筑材料功能、降低建筑能耗和调整建筑室内环境舒适度,近年来发展迅速、受到愈来愈广泛的重视,并已在建筑节能中得到了多种应用。叙述了相变材料与建筑材料复合的制备方法、研究和应用进展,对现阶段相变材料在建筑节能中的研究及其存在的问题进行了总结与分析,并指出了其进一步的研究方向。     

相变材料的新兴应用

相变材料是一类有着稳定的相变温度、且具有较大相变潜热的材料,其广泛应用在建筑节能和室内保暖方面。简要阐述了相变材料在传统建筑方面的应用,重点介绍了相变材料在药物缓释、数据存储和可穿戴设备等方面的新兴应用,从而为拓展相变材料的应用提供参考价值。     

基于矿物特性的太阳能储热材料研究进展

相变材料因其优越潜热被广泛应用于太阳能光热技术中,绝大多数有机相变材料的导热系数非常低,大多介于0.1～0.4 W·m-1·K-1之间。此外,相变材料流动性大,因此需采用导热性能好、具有稳定结构的基体支撑有机相变材料,改善其应用性能。一些天然矿物具有适当的比热与导热系数、多孔道的微结构以及天然的热稳定性与化学兼容性等矿物特性,被用于支撑相变材料制备太阳能储热材料。探讨了矿物的结构特性与性能优势,总结了石墨、珍珠岩、蛭石、硅藻土、埃洛石以及石膏等矿物基太阳能储热材料的制备研究。在此基础上介绍了矿物基太阳能储热材料在太阳能建筑节能、太阳能热水器、太阳能热发电等太阳能光热领域中的应用,并展望了矿物基太阳能储热材料的发展趋势和应用前景。     

相变蓄能材料在建筑节能方面的应用研究进展

相变蓄能材料由于相变时吸收或释放潜热的独特性能,在建筑节能方面得到了广泛的应用和研究。分析了相变材料的分类和性能,综述了国内外对相变蓄能材料基本性能的研究进展,并系统地阐述了相变蓄能材料在蓄冷空调系统以及被动式太阳房中的应用研究。     

空调蓄冷用相变材料的研究进展

本文综述了空调用相变蓄冷材料的国内外研究进展,简要介绍了相变蓄冷材料的性能要求和基本分类,总结了已有相变蓄冷材料存在的不足,并指出了优化性能的方法,特别是改善无机类材料的过冷、相分离,有机类材料的导热性能差等问题。对比了无机和有机两类材料在相变蓄冷中的优劣,并对今后空调蓄冷用相变材料的发展方向提出了建议。本文侧重强调满足空调蓄冷温区的材料,并针对典型材料展开深入调研和评述,为更好的改善空调蓄冷用相变材料的性能和推动其实际应用提供依据。     

Integrating phase change materials into concrete through microencapsulation using cenospheres

Phase change materials (PCMs) can enhance the building energy efficiency through thermal energy storage and thermal regulation. Microencapsulated PCMs (MEPCMs) provide a better utilization of PCMs with building materials. This study proposes a novel method to encapsulate PCMs into cenospheres which are hollow fly ash particles generated in coal burning power plants with size ranging from a few micrometers to hundreds of micrometers. The shell of the cenosphere inherently has some small pores which are sealed by a thin layer of glass-crystalline film. By removing this film through chemical etching, these holes can be exposed, providing paths for PCMs moving into the internal void of cenospheres. A thin layer of silica is coated on the PCM loaded cenospheres to prevent the possible leakage of liquid PCMs. The produced PCM microcapsules are referred to as CenoPCM, which can be directly added into traditional construction and building materials such as concrete to produce thermally active concrete. Prototype thermally active cement mortar integrated with the produced CenoPCM capsules have also been manufactured and characterized for its mechanical and microstructural properties. The characterizations showed that there was only minor reduction in strength and the mortar remained strong enough for building application. From this work, it is found that the produced CenoPCM capsules have great potential to be added into construction materials for reducing energy consumptions in buildings.     

墙体相变材料的研究现状与发展趋势

相变墙是含有相变建筑材料的新型墙体。综述了常用的3类相变材料(有机材料、无机材料和复合材料)的研究现状以及与混凝土墙体、石膏板、水泥沙浆等建筑材料的融合形式,并探讨了相变墙体材料的研究和发展趋势。从现有研究情况来看,单一物质很难满足各方面的要求,因而复合相变材料将是未来的主要研究和发展方向,尤其是定形相变材料,其可节省封装费用,技术经济性更好。相变材料与建筑基材的相容性、稳定性和耐久性的相关研究还有待深入。     

相变储能材料的研究进展与应用

相变储能技术对于能源的开发和合理利用具有重要意义，在太阳能利用、工业余热回收等方面有着显著的优点。综述了相变材料的研究进展，讨论了固—液相变、固—固相变储能材料的特性及其应用。固—液相变材料一般可分为无机和有机两种类型，其中无机类储能材料主要为无机盐水合物，它具有较大的溶解热和导热系数，但易出现“过冷”和“相分离”现象；有机类储能材料虽然避免了上述缺陷，但其导热性较差、溶解热较低。固—固相变材料种类较少，其中以多元醇应用最为广泛。探讨了这方面研究的发展方向，展望了储能技术市场化应用的前景。     

Phase change material based cold thermal energy storage: Materials,techniques and applications – A review

This paper gives a comprehensive review on recent developments and the previous research studies on cold thermal energy storage using phase change materials (PCM). Such commercially available PCMs having the potential to be used as material for cold energy storage are categorised and listed with their melting point and latent heat of fusion. Also techniques for improving the thermo-physical properties of PCM such as heat transfer enhancement, encapsulation, inclusion of nanostructures and shape stabilization are reviewed. The effect of stability due to the corrosion of construction materials is also reported. Finally, different applications where the PCM can be employed for cold energy storage such as free cooling of building, air-conditioning, refrigerated trucks and cold packing are discussed.     

Measurements of Heat Capacity and Enthalpy of Phase Change Materials by Adiabatic Scanning Calorimetry

Phase change materials (PCMs) are substances exhibiting phase transitions with large latent heats that can be used as thermal storage materials with a large energy storage capacity in a relatively narrow temperature range. In many practical applications the solid–liquid phase change is used. For applications accurate knowledge of different thermal parameters has to be available. In particular, the temperature dependence of the enthalpy around the phase transition has to be known with good accuracy. Usually, the phase transitions of PCMs are investigated with differential scanning calorimetry (DSC) at fast dynamic scanning rates resulting in the effective heat capacity from which the (total) heat of transition can be determined. Here we present adiabatic scanning calorimetry (ASC) as an alternative approach to arrive simultaneously at the equilibrium enthalpy curve and at the heat capacity. The applicability of ASC is illustrated with measurements on paraffin-based PCMs and on a salt hydrate PCM.     

Experimental evaluation of thermal properties of R134a clathrates based PCMs for cooling applications

The thermal properties of R134a clathrates with additives, which are treated as phase change materials (PCMs), are experimentally determined. The formation of refrigerant clathrates is investigated due to their potential use in active as well as in passive cooling applications. The PCMs are formed using R134a clathrate and distilled water with different refrigerant proportions and five different additives. The main objective of using additives is to study their potential for enhancing the clathrate thermal properties under direct contact heat transfer. PCMs are formed in glass tubes and their temperatures are recorded, at two different locations inside the tube, after regular intervals. The R134a percentages of 35% are used to form clathrate. For the additives, ethanol, sodium chloride, magnesium nitrate hexahydrate, copper and aluminum are used. PCMs are formed using a controllable constant energy water bath. The thermal properties determined are the liquid phase thermal conductivity, mushy phase thermal conductivity, and specific latent heat of the PCMs. A comparative study is conducted to compare the thermal properties of different PCMs using the suggested additives. The copper additive improves the thermal conductivity the most while sodium chloride reduces the thermal conductivity. Ethanol additive improves the specific latent heat the most while magnesium nitrate hexahydrate reduced the specific latent heat.     

建筑节能与墙体保温

我国建筑节能的核心就是对建筑物围护结构和采暖系统进行革新,其中墙体保温施工技术在建筑节能中发挥着越来越重要的作用。当今社会,发达国家都空前地重视节能问题,我国目前的单位建筑面积采暖用能耗相当于气候条件相近的发达国家的3倍~4倍,中国是一个能源比较贫瘠的国家,因此合理利用能源,提高能源利用率是我国社会发展的根本大计,而建筑物外墙围护结构节能技术的改进,保温材料的更新对社会及建筑能耗的降低具有极其重大的意义。目前我国建筑围护结构节能技术应用最多的有三种形式:一、外墙外保温;二、外墙内保温;三、夹心保温。通过优缺点列项进行对比分析后可发现,外墙外保温作法的优点最为显著,应成为我国墙体保温的主要形式以及节能建筑保温墙体的发展方向。介绍了增强粉刷石膏聚苯板、保温混凝土夹心墙、聚合物水泥聚苯板、胶粉聚苯颗粒保温浆料、硬泡聚氨酯、玻璃棉毡、大模板内置聚苯板有网和无网体系,钢框架墙体系等一系列国内外墙体保温材料和施工技术。鉴于目前外墙外保温表面粘贴面砖作法存在一定问题,使用中经常会产生脱落现象,造成安全隐患,还介绍了作者曾在实践中运用的两种施工方法——镀锌钢丝网固定抹灰贴砖法和胀栓固定加网布贴砖法,对其普遍性质量问题的处理方法特别是镀锌钢丝网和网布的安装方法及螺栓和胀栓的固定方法分别进行了详细阐述。     

Potential applications of phase change materials in concrete technology

In internal curing, pre-wetted lightweight aggregates (LWA) serve as internal reservoirs to supply the extra water needed by the cementitious and pozzolanic components of the concrete during their hydration processes. Due to their porous nature and reasonably high absorption capacity, the LWA can also be filled with other materials, such as phase change materials (PCMs). In this paper, three potential applications of PCM-filled LWA in concrete technology are presented. In addition to the previously explored application of increasing the energy storage capacity of concrete in residential and commercial construction by using a PCM with a transition temperature near room temperature, applications for higher and lower temperature PCMs also exist. In the former case, a PCM can be used to reduce the temperature rise (and subsequent rate of temperature decrease) of a large concrete section during (semi)adiabatic curing, to minimize thermal cracking, etc. In the latter case, a PCM can perhaps reduce the number or intensity of freeze/thaw cycles experienced by a bridge deck or other concrete exposed to a winter environment. In this paper, these latter two applications are preliminarily explored from both experimental and modeling viewpoints.