宁夏轻钢结构农宅采用被动式太阳能采暖的理论研究

通过对普通轻钢结构农宅和相同构造的轻钢结构被动式太阳房进行对比,计算出轻钢结构太阳房的室温及节能率,从而评价轻钢结构被动式太阳房的节能效果和经济效益。     

被动式太阳房供暖实验研究

通过对新建被动式太阳房及相同结构的对比房室内温度及室外温度、太阳辐照度等参数的监测,研究了寒冷季节室内温度随室外气象条件以及太阳辐照度的变化情况。通过分析发现,在室内无热源及辅助热源条件下,太阳房室内平均空气温度比对比房室内平均空气温度高7.2℃,最高温差达18.3℃,最低温差0.3℃。通过对太阳房供暖节能率ESF分析计算得出太阳房供暖保证率较高,证明了在此建立被动式太阳房建筑的可行性和经济性。     

应用于日光温室墙体的相变材料热物性优化研究

建立日光温室计算传热模型,以室内空气温度和墙体内表面温度为指标,通过实验方法验证了所建立的传热模型准确性,最后分析相变材料相变温度、相变焓、导热系数、密度等热物性对室内最低温度和相变蓄热率的影响规律,确定被动式相变蓄热墙体和主-被动式相变蓄热墙体的最佳相变材料热物性,阐明了实际应用时相变材料选择原则。研究结果表明,所建立的日光温室传热模型具有较高准确性,可用于日光温室墙体相变材料热物性优化;主-被动式相变蓄热墙体最佳相变材料的相变温度为27 ℃,相变焓为200 kJ/kg,导热系数为0.35 W/（m·K）,密度为440 kg/m³,被动式相变蓄热墙体最佳相变材料的相变温度为26 ℃,相变焓为200 kJ/kg,导热系数为0.35 W/（m·K）,密度为792 kg/m³;最佳相变材料热物性应用时,2种墙体室内最低温度均可达到15.0 ℃,但是被动式相变蓄热墙体的相变蓄热率较主-被动式相变蓄热墙体减小29.5%。本研究可为相变材料在日光温室的高效利用提供参考。     

浅谈被动式太阳房的应用

太阳房是直接利用太阳辐射能进行供暖。供热水或供冷的住宅。我们的祖先,将房屋砌向朝阳,开设大窗户,将阳光自然地引入室内取暖,这是最简单的太阳房;现代建筑利用太阳能进行供暖、空调、供热水、照明等,即成为现代的太阳房。１太阳房的种类 太阳房通常分为两大类。被动式和主动式,被动式太阳房,就是不用任何机械动力,将吸收的太阳能,通过空气自然循环向室内供暖。被动式太阳房具有清洁、自然舒适、构造简单、不消耗动力、造价低、故障少、维护容易等优点,但昼夜温差大,通常有直接阳光受益式、或南墙集热。蓄热墙式。主动式太阳…     

极端热环境下被动式遮阳墙体设计与节能特性研究

为了降低空调能耗在建筑能耗中所占的比例,提出了一种基于太阳高度角的被动式遮阳墙体的设计方法,在太阳高度角较大时规避太阳辐射,在高度角较小时利用太阳辐射。以南京地区某住宅为例,采用EnergyPlus软件对建筑全年负荷进行了动态模拟,分析了被动式遮阳墙体节能效果的影响因素。研究结果表明,被动式遮阳墙体能根据太阳高度角调节各个配件的尺寸,同时,采用被动式遮阳墙体的建筑比参照建筑降低了18.82%的建筑冷负荷,节能效果显著。     

我国太阳能建筑

现代建筑为满足居住者的舒适要求和使用需要,具备供暖、空调、照明等一系列功能,用太阳能代替常规能源提供建筑物的上述功能要求,即为太阳能建筑。我国太阳能建筑应用研究开始于７０年代末。当时对被动式和主动式太阳房的应用研究工作同时起步,而且进行太阳能制冷空调系统研究单位很多。因被动式太阳房更适合国情,所以８０年代重点发展被动式太阳房。近２０年来,被动式太阳房的研究工作取得很多成果,其中有的已投入实际应用,获得了良好的社会、经济效益。１被动式太阳房我国的第一栋被动式太阳房建成于１９７７年,地点在甘肃省民勤…     

附加阳光间型被动式太阳房供暖实验研究

通过对青岛地区附加阳光间型太阳房及相同结构的对比房室内温度及室外温度参数的监测,研究了寒冷季节室内温度随室外气象条件变化的情况。通过分析发现,在室内无热源及辅助热源条件下,附加阳光间型太阳房室内平均空气温度比对比房室内平均空气温度高3.8℃,最高温差达7.2℃,最低温差1.1℃。通过对附加阳光间型太阳房供暖节能率ESF分析计算得出其节能率较高的结论,证明了该地区改造被动式太阳房建筑的可行性和经济性。     

被动式太阳房隔热墙体的绝热热阻

通过对被动式太阳房隔热墙热性能的试验测试，得到了该太阳房隔热墙体的绝热热阻随墙体内外温差变化的关系．讨论了该变化关系对太阳房室内空气温度波动幅度的影响。     

被动式太阳房幻灯片

为大力推广被动式太阳房,展示我国被动式太阳房的研究成果,中国建筑工业出版社制作了一套被动式太阳房幻灯片(全套199张)。这套幻灯片汇集了全     

新型集热蓄热被动式太阳房

介绍了一种用蓄热材料建成的南向集热蓄热被动式太阳房结构和和特性,利用平板式空气太阳能集热器的特性方程分析,得出了室内温度分布的瞬态方程,并分析了该太阳房在沈阳地区24h室温及室内壁温的平均波动,根据计算,该太阳房比传统房节能96％。     

Experimental study on the thermal properties of the phase change material wall formed by different methods

The thermal properties of the shape-stabilized phase change material walls with different structure were studied. The phase change material is composed of paraffin mixture and high-density polyethylene. The walls including concrete and shape-stabilized phase change material were prepared respectively by different methods. Preparation methods include direct mixing method and lamination interpolation method. Heat transfer process in the shape-stabilized PCM walls was studied by comparing with traditional wall. The results showed that the surface temperature and the heat flow through the phase change material walls prepared by different methods are lower than that of traditional wall and the change is small. Energy-saving effect of the shape-stabilized PCM walls prepared by lamination interpolation method is better than that of the shape stabilized PCM walls by direct mixing. Results in this paper can provide the basis for the application of the shape stabilized PCM walls in the buildings.     

An organic PCM storage system with adjustable melting temperature

A proper storage temperature is an important criterion for selecting a phase change material (PCM) for a passive solar heating application. Here we describe a novel procedure to produce a mixture of carboxylic acids with a melting temperature adjustable to the climate specific requirements. The approach is based on the ideal solution model and differential scanning calorimetry (DSC). The applicability of the method is demonstrated and it is also applied to a PCM wall design. The accuracy of the theoretical model is ±2°C in the temperature range of 20°–30°C and even a ±0.5°C accuracy can be obtained by the experimental procedure.     

Investigating the performance of a test phase change material chamber for passive solar applications: experimental and theoretical approach

This paper presents the results of a numerical and experimental study for the performance of a test phase change material (PCM) chamber for passive solar applications. The numerical part of the study was based on a one-dimensional model for the phase change problem. The numerical treatment was based on a finite-difference technique and the results were compared with literature data and field measurements. The experimental test PCM chamber has been designed and developed at the campus of Central Greece University of Applied Sciences at Psachna, Evia. The PCM used in the numerical and experimental tests was GR 27 of Rubitherm. Results show that the PCM does not operate as an insulation material but as a mean of temperature stabilisation in the indoor environment during its phase change period. Regarding the application of the numerical model to simulate the performance of the experimental PCM chamber, results show good qualitative and quantitative agreement.     

TIM–PCM external wall system for solar space heating and daylighting

An external wall system for solar space heating and daylighting composed of transparent insulation material (TIM) and translucent phase change material (PCM) is presented. This system enables selective optical transmittance of solar radiation. Visible light is mainly transmitted and invisible radiation is mainly absorbed and converted to heat, causing in particular phase change. The storage medium is also the absorber. The concept of the system is presented in detail together with the investigations carried out, including a brief outline of modeling, optical experiments on PCM samples and long-term experiments on a prototype wall as well as numerical simulations. The results indicate a promising thermal–optical behavior of the system. For instance in a Swiss lowland climate (Zurich-airport) a mean energy flux of 13 W m⁻² (system efficiency 0.27) was calculated through a south facing TIM–PCM wall into the building during the month with the lowest irradiation (December). The parameters of the prototype wall with a mean melting temperature of the PCM of 26.5°C were assumed. When considering the percentage of time in which the building does not lose energy through the south facing TIM–PCM wall, a maximum can be reached with a mean melting temperature of approximately 20 to 21°C. In this case energy losses through the façade occur only during 1% of the time. With regard to the practical application of the system in buildings, aspects of reliability and durability have to be further investigated.     

Optimization of a phase change material wallboard for building use

In construction, the use of phase change materials (PCM) allows the storage/release of energy from the solar radiation and/or internal loads. The application of such materials for lightweight construction (e.g., a wood house) makes it possible to improve thermal comfort and reduce energy consumption. A wallboard composed of a new PCM material is investigated in this paper to enhance the thermal behavior of a lightweight internal partition wall. The paper focuses on the optimization of phase change material thickness. The in-house software CODYMUR is used to optimize the PCM wallboard by the means of numerical simulations. The results show that an optimal PCM thickness exists. The optimal PCM thickness value is then calculated for use in construction.     

Investigation on Phase Change Behavior of Paraffin Phase Change Material in a Spherical Capsule for Solar Thermal Storage Units

In this work, the melting and solidification behaviour of paraffin phase change material encapsulated in a stainless steel spherical container has been studied experimentally. A computational fluid dynamics analysis has also been performed for the encapsulated phase change material (PCM) during phase change process. In the melting process, the hot air, used as the heat transfer fluid enters the test section and flows over the spherical capsule resulting in the melting of phase change material. In the solidification process, the ambient air flows over the capsule and received heat from phase change material resulting in the solidification of phase change material. In the computational fluid dynamics, the constant wall boundary condition is employed for both melting (75°C) and solidification (36°C) processes since the internal conductive resistance offered by the PCM is much higher compared to the outer surface convective resistance. The time required for complete solidification and melting of the phase change material obtained from the computational fluid dynamics analysis are validated with the experimental results and a reasonable agreement is achieved. The reason for the deviation between the results are analyzed and reported.     

Impact of the Relationship between Phase Change Temperature and Boundary Temperature on the Thermal Performance of a PCM Wall and the Presentation of PCM Thermal Performance Indexes

In the composite phase change material (PCM) building envelope, the matching relationship between the phase change temperature of the PCM and the wall's boundary temperature significantly affects the energy storage performance of the PCM building envelope. In this paper, a type of concrete hollow block with a typical structure and a common PCM were adopted to produce multiform composite PCM hollow blocks, and the temperature changing hot chamber method was performed to test the thermal performance of the hollow block walls under different temperature conditions. New indexes were proposed for the thermal performance evaluation of the PCM wall. Meanwhile, combined with experimental data, the effective heat capacity model and the enthalpy model were used to analyze the effect of correlations concerning how the relationship between phase change temperature and wall's boundary temperature influenced the thermal performance of PCM wall. Three main impact factors related to temperature were obtained through the analysis. In addition, approaches for improving the thermal performance of a composite PCM wall were put forward. This paper provides the theoretical basis, data reference and practical instruction for the proper use of a PCM wall and ways for improving the thermal performance of a composite PCM wall.     

Analytical optimization of interior PCM for energy storage in a lightweight passive solar room

Lightweight envelopes are widely used in modern buildings but they lack sufficient thermal capacity for passive solar utilization. An attractive solution to increase the building thermal capacity is to incorporate phase change material (PCM) into the building envelope. In this paper, a simplified theoretical model is established to optimize an interior PCM for energy storage in a lightweight passive solar room. Analytical equations are presented to calculate the optimal phase change temperature and the total amount of latent heat capacity and to estimate the benefit of the interior PCM for energy storage. Further, as an example, the analytical optimization is applied to the interior PCM panels in a direct-gain room with realistic outdoor climatic conditions of Beijing. The analytical results agree well with the numerical results. The analytical results show that: (1) the optimal phase change temperature depends on the average indoor air temperature and the radiation absorbed by the PCM panels; (2) the interior PCM has little effect on average indoor air temperature; and (3) the amplitude of the indoor air temperature fluctuation depends on the product of surface heat transfer coefficient h_in and area A of the PCM panels in a lightweight passive solar room.     

Corrosion of metal containers for use in PCM energy storage

In recent years, thermal energy storage (TES) systems using phase change materials (PCM) have been widely studied and developed to be applied as solar energy storage units for residential heating and cooling. These systems performance is based on the latent heat due to PCM phase change, a high energy density that can be stored or released depending on the needs. PCM are normally encapsulated in containers, hence the compatibility of the container material with the PCM has to be considered in order to design a resistant container. Therefore, the main aim of this paper is to study the corrosion effects when putting in contact five selected metals (aluminium, copper, carbon steel, stainless steel 304 and stainless steel 316) with four different PCM (one inorganic mixture, one ester and two fatty acid eutectics) to be used in comfort building applications. Results showed corrosion on aluminium specimens. Hence caution must be taken when selecting it as an inorganic salt container. Despite copper has a corrosion rate range of 6–10 mg/cm² yr in the two fatty acid formulations tested, it could be used as container. Stainless steel 316 and stainless steel 304 showed great corrosion resistance (0–1 mg/cm² yr) and its use would totally be recommended with any of the studied PCM.     

An assessment of mixed type PCM-gypsum and shape-stabilized PCM plates in a building for passive solar heating

Thermal performance of two phase change material (PCM) composites, mixed type PCM-gypsum and shape-stabilized PCM plates, has been numerically evaluated in a passive solar building in Beijing with an enthalpy model. Effects of the melting temperature and phase transition zone of the PCM are analyzed and a comparison between the two types of PCM composites is performed. The results show that: (1) for the present conditions, the optimal melting temperature is about 21 °C; (2) PCM composites with a narrow phase transition zone provide better thermal performance; (3) both mixed type PCM-gypsum and shape-stabilized PCM plates effectively shave the indoor temperature swing by 46% and 56%, respectively; (4) the shape-stabilized phase change material (SSPCM) plates respond more rapidly than the mixed type PCM-gypsum and prove to be thermally more effective in terms of utilizing the latent heat.