scholarly journals ON MODELLING HEAT AND MOISTURE TRANSFER IN SANDWICH WALL AND SLAB STRUCTURES

2006 ◽  
Vol 12 (4) ◽  
pp. 337-343 ◽  
Author(s):  
Vadim Nikitin ◽  
Andrzej Lapko
Keyword(s):  
Moisture Transfer ◽  
Ambient Air ◽  
Thermal Engineering ◽  
Computational Accuracy ◽  
Heat And Moisture Transfer ◽  
Moisture Migration ◽  
Wall Structures ◽  
Sandwich Wall ◽  
Heat And Moisture ◽  
Unsteady Processes

In real wall or slab structures made of capillary‐porous materials (such as masonry or concrete) exposed to ambient air, the unsteady processes of heat transfer and moisture migration as reciprocal phenomena are observed. Basing on the Fourier general differential equations and using the assumptions of the elementary heat balance method, the problem of heat and moisture transfer has been studied in multi‐layer wall structures, such as sandwich panels. As a result the general equations were proposed and transformed into formulas useful in the FDM approach (Finite Difference Method). On this basis a computer program was written to analyse the phenomena mentioned above. Some computational tests for a concrete sandwich panel wall with insulation made of foamed polyurethane were presented and discussed to illustrate a possible application of this approach. The paper shows that the improvement of computational accuracy of modelling the thermal engineering problems requires an assumption of real parameters which characterise capillary‐porous structural materials and result from moisture transfer.

scholarly journals Modification of building energy simulation tool TRNSYS for modelling nonlinear heat and moisture transfer phenomena by TRNSYS/MATLAB integration

2020 ◽  
Vol 172 ◽  
pp. 25009
Author(s):  
Ajaya Ketan Nayak ◽  
Aya Hagishima
Keyword(s):  
Numerical Simulation ◽  
Moisture Transfer ◽  
Ambient Air ◽  
Building Energy ◽  
Energy Simulation ◽  
Modular Structure ◽  
Integration Scheme ◽  
Building Energy Simulation ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture

Software for numerical simulation of various types of energy used in buildings, i.e. building energy simulation (BES), have become an essential tool for recent research pertaining to building physics. TRNSYS is a well-known BES used in both academia and the construction industry for a wide range of simulations, such as the design and performance evaluation of buildings and related facilities for heating, cooling, and ventilation. TRNSYS has a modular structure comprising various components, and each component is interconnected and compiled through a common interface using a FORTRAN compiler. Its modular structure enables interactions with various external numerical simulation tools, such as MATLAB, Python, and ESP-r. For ordinary simulations of building energy load using TRNSYS, the generic module Type 56 is usually recommended, which provides detailed physics modelling of building thermal behaviours based on unsteady energy conservation equations and Fourier’s law for each building material. However, Type 56 explicitly depends on the transfer function method to discretise the original differential equations; therefore, it cannot model nonlinear phenomena, such as latent heat and moisture transfer between a building surface and ambient air. In other words, the current TRNSYS cannot be used to estimate the effectiveness of evaporation during cooling, which is a typical passive design method. Hence, the authors developed a MATLAB/TRNSYS integration scheme, in which TRNSYS was modified to model simultaneous heat and moisture transfer from the wet roof surface of a building. This scheme enabled TRNSYS to calculate the rate of evaporative heat and moisture transfer dynamically from the roof surface, assuming a control volume approximation of the roof surface. Finally, the effect of evaporative cooling on the thermal performance of an Indian building was estimated using the modified model.

scholarly journals Application Method of a Simplified Heat and Moisture Transfer Model of Building Construction in Residential Buildings

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4180
Author(s):  
Joowook Kim ◽  
Michael Brandemuehl
Keyword(s):  
Latent Heat ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Energy ◽  
The United States ◽  
Building Envelope ◽  
Outdoor Environment ◽  
Transfer Model ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture

Several building energy simulation programs have been developed to evaluate the indoor conditions and energy performance of buildings. As a fundamental component of heating, ventilating, and air conditioning loads, each building energy modeling tool calculates the heat and moisture exchange among the outdoor environment, building envelope, and indoor environments. This paper presents a simplified heat and moisture transfer model of the building envelope, and case studies for building performance obtained by different heat and moisture transfer models are conducted to investigate the contribution of the proposed steady-state moisture flux (SSMF) method. For the analysis, three representative humid locations in the United States are considered: Miami, Atlanta, and Chicago. The results show that the SSMF model effectively complements the latent heat transfer calculation in conduction transfer function (CTF) and effective moisture penetration depth (EMPD) models during the cooling season. In addition, it is found that the ceiling part of a building largely constitutes the latent heat generated by the SSMF model.

Simultaneous determination of thickness, thermal conductivity and porosity in textile material design

2016 ◽  
Vol 24 (1) ◽  
Author(s):  
Dinghua Xu ◽  
Peng Cui
Keyword(s):  
Thermal Conductivity ◽  
Human Body ◽  
Moisture Transfer ◽  
Least Squares Method ◽  
Weighted Least Squares ◽  
Optimal Solution ◽  
Comfort Level ◽  
Textile Material ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture

AbstractThe thickness, thermal conductivity and porosity of textile material are three key factors which determine the heat-moisture comfort level of the human body to a large extent based on the heat and moisture transfer process in the human body-clothing-environment system. This paper puts forward an Inverse Problem of Textile Thickness-Heat conductivity-Porosity Determination (IPT(THP)D) based on the steady-state model of heat and moisture transfer and the heat-moisture comfort indexes. Adopting the idea of the weighted least-squares method, we formulate IPT(THP)D into a function minimization problem. We employ the Particle Swarm Optimization (PSO) method to stochastically search the optimal solution of the objective function. We put the optimal solution into the corresponding direct problem to verify the effectiveness of the proposed numerical algorithms and the validity of the IPT(THP)D.

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