共查询到20条相似文献,搜索用时 15 毫秒
1.
Luisa F. Cabeza Cecilia Castellón Miquel Nogués Marc Medrano Ron Leppers Oihana Zubillaga 《Energy and Buildings》2007
This paper studies a new innovative concrete with phase change materials (PCM) on thermal aspects. The final objective is to develop a product which would achieve important energy savings in buildings. The work here presented is the construction and experimental installation of two real size concrete cubicles to study the effect of the inclusion of a PCM with a melting point of 26 °C. The cubicles were constructed in the locality of Puigverd of Lleida (Spain). The results of this study show the energy storage in the walls by encapsulating PCMs and the comparison with conventional concrete without PCMs leading to an improved thermal inertia as well as lower inner temperatures. 相似文献
2.
Benoit Delcroix Michaël Kummert Ahmed Daoud 《Journal of Building Performance Simulation》2017,10(4):422-437
This paper presents a model of a wall with variable properties dedicated to modelling phase change materials (PCMs) in building envelopes. The model is implemented in the TRNSYS simulation tool and referred to as Type 3258. The 1-D conduction heat transfer equation is solved using an explicit finite-difference method coupled with an enthalpy method to consider the variable PCM thermal capacity. This model includes temperature-dependent thermal conductivity and PCM-specific effects like hysteresis and supercooling. The stability conditions are discussed and the algorithm implemented in TRNSYS is described. A numerical validation performed on wall test cases proposed by the International Energy Agency is presented, showing that the developed model is in agreement with reference models. The paper also discusses the impact of temporal and spatial discretization on the model performance. Modelling problems encountered when using an effective heat capacity method (compared to an enthalpy method) and when representing supercooling are also discussed. 相似文献
3.
Experimental investigation of wallboard containing phase change material: Data for validation of numerical modeling 总被引:1,自引:0,他引:1
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 light weight construction (e.g. a wood house) makes it possible to improve thermal comfort in summer and reduce heating energy consumption in winter. The choice of a PCM depends deeply on the building structure, on the weather and on building use: numerical modeling is indispensable. In this paper, an experimental comparative study is described, using cubical test cells with and without PCM composite. A set of experimental data is detailed, concerning the air and wall temperatures. The results are compared with a numerical modeling and show that hysteresis must be taken into account to predict correctly the heat transfer. 相似文献
4.
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
5.
The use of phase change materials (PCM) and their possible architectural integration is a path in the search for optimizing energy efficiency in construction. As part of this path, a pavement has been designed which, in combination with the PCM, serves as a passive thermal conditioning system (new patent n°. ES2333092 A1) [1]. The prototype has been tested experimentally and the results proved that it is a viable constructive solution improving the energy performance of sunny locals. 相似文献
6.
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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Adequate estimation of the energetic improvements which derived from the insertion of phase change materials (PCM) inside light dry assembled walls is an important step in order to quantify the comfort advantages that can derive from the use of such materials. The use of a statistic approach based fundamentally on the time series analysis method may represent a valid information instrument in support of all the technical analysis carried out in order to evaluate the effects of thermal inertia increase on the heat transmission process that occurs between the elements of a building. PCM containing walls, tested at the “Renewable Energies Outdoor Laboratory” of the Polytechnic University of Marche during the summer of 2003, present delicate problems relative to the identification of physical models relating to dynamics of heat exchange between building components. The application of a vector auto regressive (VAR) estimation model allows, using high frequency experimental data, obtaining consistent estimates regarding the physical phenomenon of energy exchange which intervene inside buildings—both between the walls, and through the walls—occurring during the observation period. The results of this approach are twofold: firstly, they demonstrate the existence of statistically significant linear dependencies among the variables used, and secondly, they highlight the comfort conditions’ improvements due to the insertion of PCM inside dry assembled walls. 相似文献
9.
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
10.
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
11.
Development and testing of PCM doped cool colored coatings to mitigate urban heat island and cool buildings 总被引:1,自引:0,他引:1
T. Karlessi M. Santamouris A. Synnefa D. Assimakopoulos P. Didaskalopoulos K. Apostolakis 《Building and Environment》2011
In this study the performance of organic PCMs used as latent heat storage materials, when incorporated in coatings for buildings and urban fabric, is investigated. Thirty six coatings of six colors containing different quantities of PCMs in different melting points were produced. Accordingly, infrared reflective (cool) and common coatings with the same binder system and of the same color were prepared for a comparative thermal evaluation. The samples were divided in six groups of different color and eight samples each: three PCM coatings of different melting temperatures (18 °C, 24 °C, 28 °C) each one of two different PCM concentrations (20% w/w, 30% w/w), an infrared reflective and a common coating of matching color. Surface temperature of the samples was recorded at a 24 h basis during August 2008. The results demonstrate that all PCM coatings present lower surface temperatures than infrared reflective and common coatings. Analysis of the daily temperature differences showed that peak temperature differences occur between PCM and common or cool coatings from 7 am to 10 am. Investigating the temperature gradient revealed that for this time period the values for PCM coatings are lower compared to infrared reflective and common. From 10 am to 12 pm, temperature gradients for all coatings have similar values. Thus coatings containing PCMs store heat in a latent form maintaining constant surface temperatures and discharge with time delay. PCM doped cool colored coatings have the potential to enhance thermal inertia and achieve important energy savings in buildings maintaining a thermally comfortable indoor environment, while fighting urban heat island when applied on external surfaces. 相似文献
12.
Differential scanning calorimetry (DSC) is used to investigate the thermal properties of caprylic acid, 1-dodecanol and their binary system. The experimental results show that the caprylic acid/1-dodecanol binary system presents eutectic point. The eutectic melting temperature (Tem) is 6.52 °C, and the latent heat of melting of eutectic mixture (ΔHem) is 171.06 J g−1. The corresponding mass fraction of 1-dodecanol in eutectic mixture is 30%. The eutectic melting temperature and the latent heat of phase change of eutectic mixture have not obvious variations after 60 and 120 thermal cycles, which proves that the eutectic mixture has good thermal stability. 相似文献
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Modeling and simulation of under-floor electric heating system with shape-stabilized PCM plates 总被引:6,自引:0,他引:6
Kunping Lin Yinping Zhang Xu Xu Hongfa Di Rui Yang Penghua Qin 《Building and Environment》2004,39(12):1427-1434
A model is developed to analyze the thermal performance of a room applying a new kind of under-floor electric heating system with shape-stabilized phase change material (PCM) plates, which is verified by our experimental data. This system can charge heat by using cheap nighttime electricity and discharge the heat stored at daytime. The thermal performance of the heating system and the effects of various factors on it are analyzed through simulation. The results show that the heating system can be used in various climates if its structure is properly designed. The model and the discussion are helpful to design such kind of under-floor electric heating systems. 相似文献
15.
《Journal of Building Performance Simulation》2013,6(5):326-337
The TRNSYS energy analysis tool has been capable of simulating whole-building coupled heat transfer and building airflow for about 10 years. The most recent implementation was based on two TRNSYS modules, Type 56 and Type 97. Type 97 is based on a subset of the airflow calculation capabilities of the CONTAM multizone airflow and contaminant transport program developed by the National Institute of Standards and Technology. This paper describes the development of new CONTAM capabilities in support of an updated combined, multizone building heat transfer, airflow and contaminant transport simulation approach using TRNSYS. It presents an illustrative case that highlights the new coupling capability and also presents the application of this coupled simulation approach to a practical design problem of the energy use related to airflow through entry doors in non-residential buildings. 相似文献
16.
R. Parameshwaran 《Energy and Buildings》2010,42(8):1353-1360
This work aims at achieving enhanced energy conservation for space conditioning with the application of a new combined variable air volume (VAV)-based chilled water air conditioning (A/C) system and thermal energy storage (TES) system. The phase change material (PCM) used in this system exhibited good charging and discharging characteristics that directly helped in conserving the overall energy spent on cooling and ventilation. The present system was experimentally investigated for summer and winter climatic conditions under demand controlled ventilation (DCV) and DCV combined with the economizer cycle ventilation (ECV) to substantiate its energy savings capability. Based on the results, in the DCV and combined DCV-ECV modes, this system achieved 28% and 47% of per day average energy conservative potential, respectively, while compared to the conventional chilled water-based A/C system. Similarly, the VAV-TES system yielded an on-peak total energy savings of 38% and 42%, respectively, for the same operating conditions. 相似文献
17.
This paper presents the findings of a case study with building simulation using EnergyPlus dynamic thermal simulation software, in which wall insulation was varied together with cooling set-point temperature in a hot and dry climate of Botswana. Against the established norm that adding wall insulation reduces annual fuel consumption, it is shown in this paper that this is not always the case: there are instances where adding wall insulation directly increases annual fuel consumption. Initial cost of insulation aside, as the cooling set-point temperature is gradually increased, the building switches from an “insulation reduces cooling load” to an “insulation increases cooling load” behaviour. In other words, the well established knowledge that “the lower the u-value the better” gets overridden by “the higher the u-value the better”. We termed this a “point of thermal inflexion”. Simple graphical demonstration of the existence of this point is presented in the paper. According to the findings, design engineers and building economics related professionals who quantify investment on insulation can get disastrous results if they assume that all buildings behave pro-insulation since a building may behave anti-insulation. 相似文献
18.
Heat transfer and thermal storage behaviour of gypsum boards incorporating micro-encapsulated PCM 总被引:1,自引:0,他引:1
In the application of energy storage and thermal environmental control, PCM (Phase Change Material) is a very promising material choice. This study incorporated mPCM (micro-encapsulated PCM) into gypsum to make mPCM gypsum board and then investigated the physical properties, heat transfer and thermal storage behaviour. The major control parameters are wall temperatures and the weight percentages of mPCM added to the gypsum boards. A melting fraction correlation, reduced from our test data and based on Stefan number (Ste), subcooling (Sb) and Fourier number, is proposed. It shows that case with a higher Ste or Sb can have a higher heat transfer through the hot wall. Thermal storage behaviour of mPCM gypsum boards is then analyzed. 相似文献
19.
An experimental and numerical simulation study of the application of phase change materials (PCMs) in building components is presented for thermal management of a passive solar test-room. The experimental study was conducted in an outdoor test cell constituted of two small rooms separated with a wall containing PCM. A specific wall made of hollow glass bricks filled with PCM was studied. Three PCMs were tested: fatty acid, paraffin, and salt hydrate whose melting temperatures are 21 °C, 25 °C and 27.5 °C respectively.Indoor and outdoor temperatures were measured with thermocouples. Ten fluxmeters located at the centre of each wall allowed us to measure the heat fluxes across the walls. Tests were carried out in real climatic conditions.A one-dimensional numerical model has been developed to simulate the transient heat transfer process in the walls. Reasonable agreement between the simulation and the experimental results was observed. 相似文献