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Phase change materials (PCM) can be applied in building envelops to conserve heat energy. Wallboards incorporated with PCM can automatically absorb indoor redundant heat, which can greatly reduce the load of HVAC systems and save electric energy. In experiments, a PCM wallboard room was constructed by attaching PCM wallboards, developed by incorporating about 26% PCM by weight into gypsum wallboards, to the surface of an ordinary wall. The transition temperature and latent heat of these PCM wallboards were tested by differential scanning calorimetry (DSC). The room testing was conducted to determine the latent heat storage of PCM wallboards. Through experiments, it could be proved that DSC can effectively predict the performance of a full-scale installation of PCM wallboards. Compared with an ordinary room, it was found that the PCM wallboard room could greatly reduce the energy cost of HVAC systems and transfer electric power peak load to valley. 相似文献
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《Energy and Buildings》2006,38(4):357-366
In the objective to define passive components for the light envelope of buildings, different types of wallboards containing a phase change material (PCM) were studied. The high storage capacity should enable the overall thickness of wallboards to be less than 5 cm. To lower the investment costs, the wallboards were made from commercial panels after a first attempt of using gypsum walls. Three types of wallboards were studied: (i) a polycarbonate panel filled with paraffin granulates; (ii) a polycarbonate panel filled with polyethylene glycol PEG 600; (iii) a PVC panel filled with PEG 600 and coupled to a VIP. An experimental set-up was built to determine the thermal response of these wallboards to thermal solicitations. Experimental results were compared to those obtained by a numerical simulation in which an apparent heat capacity method was used. The final results show that the last studied wallboard could be used in the test cells under construction and then validate the concept. 相似文献
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For the materials with constant thermophysical properties, the thermal performance of wallboards (or floor, ceiling) can be described by decrement factor f and time lag φ. However, the phase change material (PCM) may charge large heat during the melting process and discharge large heat during the freezing process, which takes place at some certain temperature or a narrow temperature range. The behavior deviates a lot from the material with constant thermal physical properties. Therefore, it is not reasonable to analyze the thermal performance of PCM wallboard by using the decrement factor f and time lag φ. How to simply and effectively analyze the thermal performance of a PCM wallboard is an important problem. In order to analyze and evaluate the energy-efficient effects of the PCM wallboard and floor, two new parameters, i.e., modifying factor of the inner surface heat flux ‘α’ and ratio of the thermal storage ‘b’, are put forward. They can describe the thermal performance of PCM external and internal walls, respectively. The analysis and simulation methods are both applied to investigate the effects of different PCM thermophysical properties (heat of fusion Hm, melting temperature Tm and thermal conductivity k) on the thermal performance of PCM wallboard for the residential buildings. The results show that the PCM external wall can save more energy by increasing Hm, decreasing k and selecting proper Tm (α < 1); that the PCM internal wall can save more energy by increasing Hm and selecting appropriate Tm, k. The most energy-efficient approach of applying PCM in a solar house is to apply it in its internal wall. 相似文献
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《Energy and Buildings》2006,38(6):708-711
Capric acid (CA) and lauric acid (LA), as phase change materials (PCM), can be applied for energy storage in low temperature. The phase transition temperature and values of latent heat of eutectic mixtures of CA and LA are suitable for being incorporated with building materials to form phase change wallboards used for building energy storage. 120, 240 and 360 accelerated thermal cycle tests were conducted to study the changes in latent heat of fusion and melting temperature of phase change wallboards combined with the eutectic mixtures of CA and LA. Differential scanning calorimetry (DSC) tested the transition temperature and latent heat. The results showed that the melting temperature and latent heat of these phase change wallboards with eutectic mixtures have not obvious variations after repeated 360 thermal cycles, which proved that these phase change wallboards have good thermal stability for melting temperature and variations in latent heat of fusion for long time application. Therefore, they can be used for latent heat storage in the field of building energy conservation. 相似文献
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The high thermal storage capacity of phase change material (PCM) can reduce energy consumption in buildings through energy storage and release when combined with renewable energy sources, night cooling, etc. PCM boards can be used to absorb heat gains during daytime and release heat at night. In this paper, the thermal performance of an environmental chamber fitted with phase change material boards has been investigated. During a full-cycle experiment, i.e. charging–releasing cycle, the PCM boards on a wall can reduce the interior wall surface temperature during the charging process, whereas the PCM wall surface temperature is higher than that of the other walls during the heat releasing process. It is found that the heat flux density of the PCM wall in the melting zone is almost twice as large as that of ordinary wall. Also, the heat-insulation performance of a PCM wall is better than that of an ordinary wall during the charging process, while during the heat discharging process, the PCM wall releases more heat energy. The convective heat transfer coefficient of PCM wall surface calculated using equations for a normal wall material produces an underestimation of this coefficient. The high convective heat transfer coefficient for a PCM wall is due to the increased energy exchange between the wall and indoor air. 相似文献
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《Energy and Buildings》2006,38(6):673-681
Light envelopes are more and more frequently used in modern buildings but they do not present sufficient thermal inertia. A solution to increase this inertia is to incorporate a phase change material (PCM) in this envelope. This paper presents the performance of a test-cell with a new structure of light wallboards containing PCMs submitted to climatic variation and a comparison is made with a test-cell without PCMs. To improve the wallboard efficiency a vacuum insulation panel (VIP) was associated to the PCM panel. This new structure allows the apparent heat capacity of the building to be increased, the solar energy transmitted by windows to be stored without raising the indoor cell temperature, and the thickness of the wallboard to be decreased compared with that of traditional wallboards. An experimental study was carried out by measuring temperature and heat fluxes on and through the wallboards. The indoor temperature, which has a special importance for occupants, was also measured.A numerical simulation with the TRNSYS software was carried out in adding a new module representing the new wallboard. It showed a good agreement with experimental results. This new tool will allow users to simulate the thermal behaviour of buildings having walls with PCMs. 相似文献
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《Energy and Buildings》2006,38(1):18-24
Through combining gypsum boards with phase change materials (PCM), the compound phase change wallboards are formed. The transition temperature and latent heat of these phase change wallboards are tested by differential scanning calorimetry (DSC). The results indicate that these phase change wallboards can be applied in buildings to save energy cost and electric power. Then, the thermal properties of phase change wallboards are analyzed. The phase change wall room and the ordinary wall room are experimented and compared under the climatic conditions in winter in the northeast of China. The impact on the indoor temperature, surface temperature of wallboards and thermal flow through wall are achieved. Finally, it can be got that the phase change wallboards can improve indoor thermal environment. 相似文献
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《Energy and Buildings》2006,38(10):1262-1269
Shape-stabilized phase change material (PCM) is a kind of novel PCM. It has the following salient features: large apparent specific heat for phase change temperature region, suitable thermal conductivity, keeping shape stabilized in the phase change process and no need for containers. The preparation for such kind material was investigated and its thermophysical properties were measured. Some applications of such material in energy efficient buildings (e.g., in electric under floor space heating system, in wallboard or floor to absorb solar energy to narrow the temperature swing of a day in winter) were studied. Some models of analyzing the thermal performance of the systems were developed, which were validated with the experiments. The following conclusions are obtained: (1) the applications of the novel PCM we put forward are of promising perspectives in some climate regions; (2) by using different paraffin, the melting temperature of shape-stabilized PCM can be adjusted; (3) the heat of fusion of it is in the range of 62–138 kJ kg−1; (4) for PCM floor or wallboard to absorb solar energy to narrow the temperature swing in a day in winter, the suitable melting temperature of PCM should be a little higher than average indoor air temperature of the room without PCM for the period of sunshine; (5) for the electric under-floor space heating system, the optimal melting temperature can be determined by simulation; (6) PCM layer used in the aforementioned application should not be thicker than 2 cm; (7) the models developed by us are helpful for applications of shape-stabilized PCM in buildings. 相似文献
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相变材料在建筑中的应用 总被引:11,自引:3,他引:8
相变材料是一种高效的贮热物质。在一定的温度下,它发生相变,并伴随着吸热、放热。根据相变材料化学成分、相变过程形态和相变温度,相变材料可以分为不同的种类。相变材料结合微胶囊技术制造的相变材料微胶囊具有导热系数好,易于与建筑材料结合,经济等优点。本文介绍了相变材料在墙体、混凝土制品、地板中的应用,以达到节能和室内舒适的目的,并指出了今后还需要进一步研究的一些问题。 相似文献
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A wallboard new PCM material is experimentally investigated in this paper to enhance the thermal behavior of light weight building internal partition wall. The experiments are carried out in a full-scale test room which is completely controlled. The external temperature and radiative flux dynamically simulate a summer repetitive day. The differential test concern walls with and without PCM material under the same conditions. The PCM allows to reduce the room air temperature fluctuations, in particular when overheating occurs. A numerical modeling has been used to investigate energy storage. Five millimeters of PCM wallboard double the energy that can be stocked, and destocked, during the experiment. The experiments are fully described so that the results can be used for the validation of numerical models dealing with phase change materials. 相似文献
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本文从相变墙体冬季的传热过程出发,提出“保温因子”和“放热因子”评价其传热性能。然后,利用热阻法建立相变墙体在冬季的传热模型,并利用单因素分析的方法研究相变墙体内外层热阻和相变温度对“保温因子”和“放热因子”的影响,结果显示当相变墙体的作用是保温的情况下,相变层应布置在墙体的外侧,相变温度应该接近室内空气温度。当相变墙体的作用是放热的情况下,相变层应布置在墙体的内侧,相变温度应该尽量高一些。本研究可以为相变墙体的应用提供理论支持。 相似文献
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An air source heat pump water heater with phase change material (PCM) for thermal storage was designed to take advantage of off-peak electrical energy. The heat transfer model of PCM was based upon a pure conduction formulation. Quasi-steady state method was used to calculate the temperature distribution and phase front location of PCM during thermal storage process. Temperature and thermal resistance iteration approach has been developed for the analysis of temperature variation of heat transfer fluid (HTF) and phase front location of PCM during thermal release process. To test the physical validity of the calculational results, experimental studies about storing heat and releasing heat of PCM were carried. Comparison between the calculational results and the experimental data shows good agreement. Graphical results including system pressure and input power of heat pump, time-wise variation of stored and released thermal energy of PCM were presented and discussed. 相似文献
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Novel concept of composite phase change material wall system for year-round thermal energy savings 总被引:1,自引:0,他引:1
A new type of composite wall system incorporating phase change materials (PCMs) was proposed and its potential for air conditioning/heating energy savings in continental temperate climate was evaluated. The novelty of the wall system consists of the fact that two PCM wallboards, impregnated with different PCMs are used. The structure of the new wall system is that of a three-layer sandwich-type insulating panel with outer layers consisting of PCM wallboards and middle layer conventional thermal insulation. The PCM wallboard layers have different functions: the external layer has a higher value of the PCM melting point and it is active during hot season and the internal layer with a PCM melting point near set point temperature for heating is active during cold season. A year-round simulation of a room built using the new wall system was carried out and the effect of PCM presence into the structure of the wall system was assessed. It was found that the new wall system contributes to annual energy savings and reduces the peak value of the cooling/heating loads. The melting point values for the two PCMs resulting in the highest value of the energy savings were identified. 相似文献
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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. 相似文献
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本文首先阐述了利用拉氏变换确定多重相变温度和材料用量的原理,而后导出了利用反应系数法计算多重相变温度和材料用量的方法,最后以厦门普通屋面为例,分析说明了该理论与方法的具体应用.实例分析结果表明:内、外侧热作用引起的围护结构中的温度和热流变动可分解为单侧热作用引起的变动值的迭加;单侧热作用引起的围护结构中的温度和热流变动可用反应系数法来计算,温度反应系数和热流反应系数可分别由式(12)和式(13)计算确定;多重相变温度和材料用量可分别按式(14)和式(17)计算确定;当多重相变材料用于建筑外表面隔热时,相变温度可基于室外综合温度日平均值来确定;利用多重相变材料进行建筑隔热一般只需几毫米的相变层厚度. 相似文献