共查询到20条相似文献,搜索用时 31 毫秒
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The sustainable world's economic growth and people's life improvement greatly depend on the use of alternative products in the architecture and construction, such as industrial wastes conventionally called green materials. For this purpose, hemp concrete is more and more recommended by the eco-builders because hemp is a renewable plant, recyclable and does not degrade within time. It corresponds perfectly to the requirements of high environmental quality buildings. The objective of this article is to study transient hygrothermal behaviour of hemp concrete at whole building level. The physical model is one-dimensional and was implemented into the object-oriented simulation environment SPARK, using the finite difference technique with an implicit scheme. The numerical result showed that the use of hemp concrete wall in buildings can ensure good indoor air quality and energy savings in winter. Besides, the combined effect of moisture buffering with the adequate ventilation strategies increases hemp concrete building performance. Our results also suggest that taking into account the hygrothermal transfer at whole building level with heat and moisture production sources has significant effects on predictions. 相似文献
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In this paper a modified two-dimensional Luikov model for evaluating the non-isothermal moisture migration in porous building materials was proposed. The coupled heat and moisture transfer problem was modeled. Vapor content and temperature were chosen as the principal driving potentials. The coupled equations were solved by a numerical method, which consists of a finite difference technique with a fully implicit scheme in time. Two validation experiments were developed in this study. The evolution of transient moisture distributions in both one-dimensional and two-dimensional cases was measured. A comparison between experimental results and those obtained by the numerical model proves that they are fully consistent with each other. The modified model can be integrated into a whole building heat, air and moisture transfer model. 相似文献
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A study of coupled heat and mass transfer across a porous building component in intertropical conditions 总被引:2,自引:0,他引:2
In this paper, one-dimensional coupled heat and mass transfer through a plane geometry porous building component submitted to intertropical climatic conditions is studied. An analytical method using the periodic solution approach has been proposed to evaluate the heat and moisture transfer process in building materials. Results are discussed using the three climatic regions of Cameroon (2-13 °N). With latitude of 11°, it offers examples of practically whole range of intertropical climates. Influence of latitude on various temperature and moisture content through the building component has been presented. The results are in good agreement with the experimental data and other analytical solutions published in the literature. 相似文献
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Menghao Qin Rafik Belarbi Abdelkarim Aït-Mokhtar Francis Allard 《Automation in Construction》2009,18(5):624-631
The simultaneous heat and moisture transfer in the building envelope has an important influence on the indoor environment and the overall performance of buildings. In this paper, a model for predicting whole building heat and moisture transfer was presented. Both heat and moisture transfer in the building envelope and indoor air were simultaneously considered; their interactions were modeled. The coupled model takes into account most of the main hygrothermal effects in buildings. The coupled system model was implemented in MATLAB-Simulink, and validated by using a series of published testing tools. The new program was applied to investigate the moisture transfer effect on indoor air humidity and building energy consumption under different climates. The results show that the use of more detailed simulation routines can result in improvements to the building's design for energy optimisation through the choice of proper hygroscopic materials, which would not be indicated by simpler calculation techniques. 相似文献
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文中籍Ansys热分析技术原理,较为详细地讨论了具有相同孔型布置的砌砌块和具有相同导热系数的砂浆,因为砂浆敷设方式的不同对墙体传热系数的影响,同时也分析了不同孔型布置方式对砌块本体传热系数的作用。通过研究,认为只有合理设计砌块的孔型布置,选择正确的砌块间砂浆敷设方式,才能够有效地降低墙体围护材料的传热系数,提高墙体围护材料的阻热能力。Ansys热分析技术实质上是一种数值计算方法,可广泛地应用于空心砌块以及多孔烧结制品材料,能够在墙体制品(含烧结制品)材料的体型设计阶段,为有效地降低制品的传热系数、提高阻热能力提供科学、有效的佐证。 相似文献
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Anh Dung Tran Le Chadi Maalouf Omar Douzane Geoffrey Promis Ton Hoang Mai Thierry Langlet 《Journal of Building Performance Simulation》2016,9(6):589-605
In this article, a hygrothermal building model, taking into account the building envelope, indoor heat and moisture sources, indoor environment and moisture buffering capacity of interior objects, is presented and validated with the test cases found in the literature. The model is used to study the impact of hemp concrete and the moisture buffer capacity of the interior elements on the prediction of the hygrothermal comfort in the building. The numerical results show that the use of hemp concrete in buildings can ensure good hygrothermal comfort. Besides, taking into account the effect of moisture buffering of indoor objects increases the building performance. Our results also suggest that neglecting moisture transfer through the envelope increases significantly the predicted percentage of dissatisfied indices and reduces the acceptability of indoor air quality during the occupied period. This study also confirmed that the combined relative humidity-sensitive ventilation system and moisture buffering capacity of building envelope and of interior objects is a very efficient way to reduce the heating energy consumption. 相似文献
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《Building and Environment》2001,36(5):579-588
Moisture transfer in building components and furnishings has significant effect on indoor air humidity and latent cooling load. Many mathematical models and calculation methods have been proposed to evaluate this effect. Simple but accurate models are what the users expect. Investigation shows that the one-dimensional linear moisture transfer model, which uses the vapor pressure as the unique driving potential, is both very simple and well match the real moisture transfer characteristics of most air-conditioned buildings. Frequency analysis shows completely consistent characteristics between the transfer function model of moisture sorption by interior surface materials and the one-dimensional linear moisture transfer model through the entire wall within the frequency range that should be concerned. It also shows that the moisture penetration across the wall is neglectable. The transfer function model of moisture sorption by interior surface materials is not only very simple but also has satisfactory accuracy to evaluate the moisture transfer effect of buildings on indoor air humidity and latent cooling load. 相似文献
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Contribution to analytical and numerical study of combined heat and moisture transfers in porous building materials 总被引:2,自引:0,他引:2
In this paper, one-dimensional model for evaluating coupled heat and moisture transfer in porous building materials was proposed. The transient partial differential equations system was solved analytically for Dirichlet boundary conditions. It consists first to introduce the Laplace transformation and then to use the potential function technique. This approach allows simplifying the initial mathematical problem to a fourth order ordinary differential equation which can be easily solved. This solution was used to assess the transient temperature and moisture distribution across materials. A comparison with numerical models from Luikov [2] and Vafai et al. [12] was performed, a good agreement was obtained. 相似文献
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《Energy and Buildings》2006,38(4):303-314
In order to precisely predict ground heat transfer, room air temperature and humidity, a combined model has been developed and conceived to calculate both the coupled heat and moisture transfer in soil and floor and the psychrometrics condition of indoor air. The present methodology for the soil is based on the theory of Philip and De Vries, using variable thermophysical properties for different materials. The governing equations were discretized using the finite-volume method and a three-dimensional model for describing the physical phenomena of heat and mass transfer in unsaturated moist porous soils and floor. Additionally, a lumped transient approach for a building room and a finite-volume multi-layer model for the building envelope have been developed to integrate with the soil model. Results are presented in terms of temperature, humidity and heat flux at the interface between room air and the floor, showing the importance of the approach presented and the model robustness for long-term simulations with a high time step. 相似文献
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The hygrothermal storage characteristics of an underground building envelope have discernible effects on the heat and humidity of the indoor environment. To predict the hygrothermal storage capacity, it is necessary to accurately calculate the transient heat and moisture flux through the envelope. This paper describes the development of a new hygrothermal model described with relative humidity and temperature based on the results of existing researches. The moisture model fully states actual moisture transfer process involving both vapor diffusion and liquid water migration in porous building envelopes. Verified using the results calculated by the mathematical model of Mendes et al., the new hygrothermal model can accurately predict the heat and moisture transfer of building envelopes. Hygrothermal absorption and desorption of three types of common underground building envelopes in Chengdu region in China are analyzed by using the new model. The results show that the hygrothermal absorption and desorption of underground building envelopes must be considered when the heat and moisture environment is controlled by HVAC. Taking account of these factors can reduce air-conditioning equipment capacity and save running energy. 相似文献
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针对回热式新风系统中多孔介质回热器在交替边界条件下的传热传质特性进行了研究。采用数值方法针对表面温、湿度交替变化的对流边界条件,对多孔床与空气的非稳态传热传质过程进行了模拟计算,获得了多孔床内温度场和含湿量场。在此基础上,分析了该类多孔床的传热传质特性,并比较了关键因素对多孔床内温度和含湿量变化的影响。计算结果表明,多孔床与空气之间的热质交换主要发生在交界面附近较浅的薄层,往底层的传递十分缓慢。多孔床与空气的热、质交换效果受气流流速影响较为明显。 相似文献
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Heat and mass coupled transfer combined with freezing process in building materials: Modeling and experimental verification 总被引:1,自引:0,他引:1
Newly completed building envelope is always characterized by high initial moisture content, and so the liquid moisture permeability is the main feature of mass transferring on its initial use. The high initial moisture content has strong impact on indoor condition and energy consumption especially in severe cold area where the moisture freezing in building envelope would occur in winter. Therefore, accurately predicting the hygrothermal states of building envelope to obtain useful envelope parameters is very important. In order to analyze the moisture transferring performance of enclosure on building initial use in severe cold area, the paper studied the coupling transfer of heat and moisture in building envelope. The permeability and freezing of the liquid water in porous building material were considered. The moisture content gradient was used as mass transfer driving force, and the temperature gradient was used as heat transfer driving forces. Heat and moisture coupled transfer conservation equations on different transferring conditions were built. An experimental set-up was built to verify the model, and good agreements were obtained, which suggests that the model can be used to simulate the heat and moisture coupled transfer in newly completed building envelope of severe cold area. 相似文献