高温相变蓄热材料研究进展

本文通过对高温相变蓄热材料国内外研究现状进行分析,提出探索高温相变蓄热过程热力学行为特性,建立热-结构耦合分析模型,并与实验研究相结合,是弄清相变过程热力学机理、掌握相变蓄热技术、进行吸热/蓄热器和热控系统以及相变蓄热容器合理设计的关键,并将为最终在太阳能发电、高温热能回收、航天以及冶金等其它工业领域的技术应用奠定基础。     

粉煤灰基高温复合相变蓄热材料的制备

复合相变蓄热材料目前广泛应用在太阳能和工业余热的回收方面,可解决在时间、空间上能源分配的失调,成为高温相变蓄热材料的最主要研究方向之一。我们以大同二电厂的垃圾粉煤灰为基体材料,预处理后与相变材料铝粉一起采用混合烧结法制出铝粉/粉煤灰基高温复合相变蓄热材料。采用XRD,SEM等测试分析技术对材料的组织结构与热物性能进行表征,结果表明,粉煤灰基复合相变蓄热材料成品各组分分布较均匀,具有十分优良的成形性和烧结性。     

高温相变蓄热技术

节能环保是当今社会的热点话题，寻找新的环境友好型能源及行之有效的节能技术已经成为一个迫切的课题。相变蓄热技术作为一种高效环保的节能技术，一直受到关注。但对于它的研究大多集中于中低温蓄热技术。本文将重点介绍高温相变蓄热材料的工作原理，以及高温相变蓄热技术作为一种新的节能技术的应用前景。     

高新区电蓄热供热系统分析

介绍了电锅炉蓄热系统的工作原理及意义,根据蓄热系统的设计原则,从电锅炉、高温蓄热装置、智能化自控系统等方面,阐述了蓄热系统的组成及作用,并通过实例计算说明了电蓄热供热系统经济合理,技术可行。     

电热锅炉承压高温蓄热系统及其工程应用

回顾了供热、空调系统的蓄热分类,着重介绍了电热锅炉蓄热系统.对电热锅炉承压高温蓄热系统的组成、技术优势及经济效益作了初步探讨,并提供了这种蓄热系统的一个设计实例.     

显热、潜热蓄热技术在道路热红外伪装中的应用研究

针对工程道路热红外伪装问题,探索了显热蓄热、潜热蓄热技术在热红外伪装方面应用问题.道路的温度随气象、地域和时分的不同变化很大,应用潜热蓄热技术进行红外伪装时,需要采用相变温度分割法或使用非晶体相变材料.由此提出使用商品石蜡并分析了其各项特点,指出当前还需要有效解决蓄热系统的热力学特征的模拟计算和相变材料的掺混工艺问题....     

相变蓄能技术及其在节能建筑中的应用

该文首先介绍了用于固液相变的相变材料,随后综述了目前相变蓄能技术的研究内容和方向.包括间壁式相变蓄热、直接接触式相变蓄热、相变围护结构等蓄热技术和用于空调通风系统以及制冷系统的固液相变蓄冷技术.最后提出我国节能建筑可大力发展利用相变蓄热技术的被动式太阳房和相变蓄冷空调系统.     

高温相变电蓄热供暖装置的研究

对比了目前北方几种常见的供暖方式,总结了电蓄热供暖的特点。采用铝硅合金作为相变材料,设计了一种高温相变电蓄热供暖装置,并对其蓄热和热能输出特性进行了研究分析。     

相变储能技术的研究和发展

相变储热技术是利用低品位能源，实现建筑节能的重要途径。相变储能在建筑节能和暖通空调领域中的应用越来越受到重视，已成为国际研究的热点。研究了在储能领域使用较为广泛的相变材料的种类及其特点。分析了国内外相变储能理论与技术的发展现状以及相变材料在建筑围护结构、太阳房供暖系统、电热蓄热系统及蓄冷空调中的应用。展望了相变材料在蓄能技术方面的发展前景。     

利用冶炼钢渣配制蓄热混凝土

选用热容大的玄武岩、冶炼钢渣为集料,硅酸盐水泥作为蓄热材料的胶凝剂,添加矿渣粉和硅微粉提高了蓄热材料力学性能,掺入一定比例石墨粉改善了蓄热材料热学性能,所制备的蓄热混凝土在200~500℃高温阶段抗压、抗折强度综合性能表现突出,在温差300~500℃,其平均比热为2272J/(kg·K),每m3蓄热混凝土的理论蓄热量可达335.75kWh。     

Energiespeicherbeton – ein Beton mit integriertem Latentwärmespeichermaterial

Energy storage concrete – a concrete with integrated latent heat storage material. In times of solar architecture and increased utilisation of renew‐able energy, building components with high thermal heat storage capability are becoming increasingly important. One of the areas future research in building physics and building services will focus on is the development of energy storage units. A particularly interesting research area is latent heat storage. This essay describes the development of a concrete with integrated latent heat storage material (phase change material, PCM) as part of a thesis. This innovative concrete offers significantly improved thermal characteristics. For example, it was possible to more than double the heat capacity within a temperature range of 10 Kelvin around the melting point of the PCM. The PCM has a melting point between approx. 22 °C and 35 °C, depending on application. A highly versatile material such concrete offers a wide range of application options. In principle, it is possible to use latent heat storage concrete to supplement heating systems, to extend the scope of passive solar systems, or to protect against overheating in summer.     

香烟引燃特性的实验研究

通过香烟火源引燃几种家庭常见物品的实验,研究香烟火的引燃特性。实验结果显示:香烟火温度虽高,但不一定引起有焰燃烧,可能只有炭化痕迹或持续阴燃;判断材料有无蓄热能力,不能只考虑材料自身组分的燃烧特性,而是要具体问题具体分析;蓄热材料也不一定能被香烟火点燃;阴燃反应相对缓慢,产生较多有毒气体,没有火焰,潜伏期长,不易察觉。     

三套管相变蓄能换热器供热工况稳态模拟分析

三套管相变蓄能换热器在供热工况下运行时,外层水与中间层相变材料间的换热以及中间层相变材料与内层制冷剂间换热同时进行。建立了三套管相变蓄能换热器的数学模型,针对液态相变材料层引入了有效热导率,模拟稳态下传热温度场。三套管相变蓄能换热器的液态相变材料层增大了传热热阻,产生较大的径向温度梯度,但30min后相变材料层温度场即可达到稳态,制冷剂侧换热效果并未由于相变材料热导率低而有显著变化。     

泡沫铜/石蜡复合相变材料融化过程的换热特性

为了研究强化相变蓄热器的换热情况,搭建了矩形腔体内填充泡沫金属/石蜡的实验台,在恒壁温条件下,进行了泡沫金属/石蜡复合相变材料的融化蓄热实验.根据实验数据绘制了不同加热温度下石蜡内部温度随时间变化曲线,分析了腔体内自然对流对温度分布的影响、传热温差对蓄热时间的影响.结果表明,泡沫金属的高导热性能强化了石蜡在腔体内的融化...     

定形相变材料的制备及对混凝土耐高温性能的影响

为了提高混凝土结构的耐高温性能,从混凝土自身的储热性能出发,制备了一种定形相变材料,并研究了该相变材料对混凝土导热性能和高温后力学强度的影响。结果显示:硫酸铝铵掺量越高,相变材料的相变焓越大,当其掺量超过70%时,差示扫描量热法(DSC)特征参数趋于稳定;定形相变材料具有较好的热稳定性,且高温下硫酸铝铵和SiO2并未发生化学反应;相变材料的加入能提高混凝土的储能密度,降低其导热系数,混凝土内部的温度随相变材料掺量的增多而逐渐降低;当相变材料掺量小于6.5%时,相变材料的加入能明显提高混凝土高温后的强度,而当相变材料掺量大于6.5%时,再提高其掺量对混凝土耐高温性能的改善作用有限。     

Effect of double layer phase change material in building roof for year round thermal management

Efficient and economical technology that can be used to store large amounts of heat or cold in a definite volume is the subject of research for a long time. Latent heat storage in a phase change material (PCM) is very attractive because of its high-energy storage density and its isothermal behavior during the phase change process. Thermal storage plays a major role in building energy conservation, which is greatly assisted by the incorporation of latent heat storage in building products. Increasing the thermal storage capacity of a building can enhance human comfort by decreasing the frequency of internal air temperature swings so that the indoor air temperature is closer to the desired temperature for a longer period of time. However, it is impossible to select a phase change material to suit all the weather condition in a given location. The PCM that reduces the internal air temperature swing during the winter season is not suitable for the summer season as the PCM remains in the liquid state at all the times during these months and hence the system cannot exploit the latent heat effect. This paper attempts to study the thermal performance of an inorganic eutectic PCM based thermal storage system for thermal management in a residential building. The system has been analyzed by theoretical and experimental investigation. A double layer PCM concept is studied in detail to achieve year round thermal management in a passive manner.     

相变微囊复合建材制备及储放热研究

通过采用微乳化技术,将水分散于常温相变储能石蜡中;应用膜孔法,以海藻酸钠包封常温相变石蜡,制得储能微囊;将微囊与石膏基体复合后,制备得到储能建筑材料.研究发现:储能微囊为球形,其粒度分布范围窄;相变含水石蜡微囊储能建筑材料的储能密度得到显著提高,在低于常温相变石蜡固-液相变温度下,其导热系数减小,储/放热时间明显延长,对环境温度的变化响应滞后时间加大,维持恒定温度的时间得到较大延长.     

Effects of wallboard design parameters on the thermal storage in buildings

The phase change material (PCM) could be added to the wallboard to increase the thermal mass to decrease in indoor temperature fluctuation and improve thermal comfort. In this study, experimentally validated simulation was performed to investigate the effects of various parameters of PCM including the nominal average phase change temperature, its range, the convective heat transfer coefficients and the wallboard thickness on the thermal storage performance of the wallboard such as the thermal energy storage and the time shift.It was found that the average phase change temperature should be close to the average room temperature to maximize the thermal heat storage in the wallboards. The phase change temperature should be narrow to maximize the thermal heat storage in the PCM wallboards. The thermal heat storage increased with the convective heat transfer coefficient, and the optimal average phase change temperature to maximize the storage shifted a bit to a higher temperature with it. The time shift was found to decrease with the convective heat transfer coefficient and the phase change temperature range.     

Preparation and application effects of a novel form-stable phase change material as the thermal storage layer of an electric floor heating system

A novel form-stable phase change material (FSPCM) was prepared, which comprises micro-encapsulated paraffin (MEP) as the latent heat storage medium and high density polyethylene/wood flour composite as the matrix. It has the following merits: proper phase transition temperature, large apparent specific heat in phase change temperature region, suitable thermal conductivity, good shape retention and dimensional stability. Therefore, it is suitable for the applications in energy efficient buildings without encapsulation. Simulation studies were performed to investigate the temperature-regulating and cost-reduction effects of the FSPCM as the thermal storage layer (TSL) material of an electric floor heating system (EFHS). The results show that it is promising to use the FSPCM plate as the TSL to achieve better temperature-regulating and cost-reduction effects, and the application effects depend on the heating mode of the EFHS and the thickness of FSPCM plates. The cost-benefit analysis indicates also that the prepared FSPCM has the potential to serve as the TSL in an electric floor heating system.     

A comparative performance study of some thermal storage materials used for solar space heating

One of the most common methods used in passive heating is the utilization of a massive wall for heat storage. Many factors affect the performance of the wall, such as the thickness and the media used for heat storage. A numerical study has been conducted on a zone heated by a thermal storage wall. Three different storage materials are examined, namely concrete, the hydrated salt CaCl₂·6H₂O and paraffin wax (N-eicosane). A numerical model is presented in this paper which judges the suitability of these materials as thermal storage mediums under the actual weather conditions of Iraq. For that purpose, the room temperature fluctuation in the zone is evaluated for each material using different thickness for each wall. The study concluded that an 8-cm-thick storage wall made from the hydrated salt is capable of maintaining the comfort temperature in the zone with the least room temperature fluctuation.