A method for predicting heat and moisture transfer through multilayered walls based on temperature and moisture content gradients

2005 ◽  
Vol 48 (1) ◽  
pp. 37-51 ◽  
Author(s):  
N. Mendes ◽  
P.C. Philippi
Keyword(s):  
Moisture Content ◽  
Moisture Transfer ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture

A hybrid analytical–numerical method for computing coupled temperature and moisture content fields in porous soils

2017 ◽  
Vol 42 (1) ◽  
pp. 68-94 ◽  
Author(s):  
Suelen Gasparin ◽  
Marx Chhay ◽  
Julien Berger ◽  
Nathan Mendes
Keyword(s):  
Moisture Content ◽  
Analytical Solutions ◽  
Numerical Solutions ◽  
Moisture Transfer ◽  
Physical Phenomenon ◽  
Computational Cost ◽  
Analytical Models ◽  
Heat And Moisture Transfer ◽  
Porous Soils ◽  
Heat And Moisture

This work is devoted to proposing a hybrid numerical–analytical method to address the problem of heat and moisture transfer in porous soils. Several numerical and analytical models have been used to study heat and moisture transfer. The complexity of the coupled transfer in soils is such that analytical solutions exist only for limited problems, while numerical solutions can deal with more realistic ones but at a higher computational cost. Therefore, we propose to implement analytical solutions where variations of temperature and moisture content are known to be almost nonvarying, while the numerical solution is implemented in the remaining region, near the boundaries. The coupling between solutions is performed assuming the continuity of both fields and fluxes at each interface. This strategy allows assuring the physical phenomenon occurring at the interface. Numerical experiments are performed, showing the accuracy, the efficiency, and the great potential of the method regarding applications in nonlinear soil problems.

Heat and moisture transfer performance of thin cotton fabric under impingement drying

2018 ◽  
Vol 89 (15) ◽  
pp. 3089-3097
Author(s):  
Miao Qian ◽  
Jinghan Wang ◽  
Zhong Xiang ◽  
Zhewei Zhao ◽  
Xudong Hu
Keyword(s):  
Moisture Content ◽  
Cotton Fabric ◽  
Moisture Transfer ◽  
Transfer Model ◽  
Transfer Performance ◽  
Heat And Moisture Transfer ◽  
Drying Time ◽  
Uniform Distributions ◽  
Heat And Moisture ◽  
Over Time

To investigate the drying characteristics of thin cotton fabric for reducing the energy consumption during the heat setting process, a two-dimensional heat and moisture transfer model considering lateral heat and moisture transmission under the impingement drying condition was developed in this study. The curves of the variation in fabric temperature and moisture content over time were obtained and the results indicate that the drying rate increases with the decrease in the moisture content in the fabric. In addition, non-uniform distributions of temperature and moisture on the fabric over time were obtained. The drying time per unit area on the fabric was found to increase with time. Further, experiments were conducted to test the heat and moisture transfer performance of the fabric, and the experimental results agree reasonably well with the calculations.

scholarly journals The use of cellular automata in modeling the processes of wood drying in a stack

2021 ◽  
Vol 3 (2) ◽  
pp. 39-44
Author(s):  
Ya. I. Sokolovskyy ◽  
◽  
O. V. Sinkevych ◽  
Keyword(s):  
Cellular Automata ◽  
Moisture Content ◽  
Relative Error ◽  
Moisture Transfer ◽  
Physical Characteristics ◽  
Cad Model ◽  
Wood Drying ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture ◽  
Drying Chamber

In this work, we investigated the possibilities of using a model of cellular automata in solving the problem of heat and moisture transfer in a periodic wood drying chamber. Thus, in this work are investigating the processes of heat and moisture transfer between the wood and its drying agent. Studies are carried out by using CAD model of stack of dried wood. To use cellular automata, it is proposed to present the CAD model as an array of cubes, each of which has six faces (cells). In this work also proposes to use the different research zones, each of which allows us to calculate the values of temperature and moisture content in different places of the CAD model. In particular, these zones can be placed inside the wood, on its boundary or in the agent of its drying. The proposed cell-automata model contains local relationships between cells that describe their general behavior. In addition to describing the general behavior of cells, the model provides the possibility of setting the physical characteristics of the material. This allows us to approximate processes and determine new values of the physical characteristics of the material, including temperature and moisture content. The proposed algorithm for the use of cellular automata makes it possible to obtain a reliable result unnecessarily to conduct complex and expensive practical experiments. To speed up the calculation process, propose to use multilayered, which consists in obtaining numerical values of the physical characteristics of the material from several adjacent cells, which are located in the same direction of interaction. The work also provides graphs of changes in temperature and relative humidity of the wood drying agent. In this work is also given graphs of changes in temperature and moisture content of wood inside and on its boundary. To check the adequacy and reliability, all results are compared with the results of another experiment. To check the adequacy and reliability, we compared the obtained results with the results of another experiment. For this comparison in work it is calculated the relative error between the temperature and moisture content values of both experiments. The value of this relative error makes it possible to determine the prospects for the use of cellular automata in the simulation of heat and moisture transfer processes in wood drying chambers. Keywords: сellular automata; CAD model; algorithm of work; transition rules; wood drying chamber.

scholarly journals Mathematical modeling and research of heat and moisture transfer processes in porous media

2021 ◽  
Vol 264 ◽  
pp. 01038
Author(s):  
Normakhmad Ravshanov ◽  
Istam Shadmanov ◽  
Kurash Kubyashev ◽  
Sanjar Khikmatullaev
Keyword(s):  
Porous Media ◽  
Moisture Content ◽  
Numerical Algorithm ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Internal Heat ◽  
Effect Of Temperature ◽  
Heat And Moisture Transfer ◽  
Managerial Decisions ◽  
Heat And Moisture

A mathematical model, numerical algorithm, solution, and results of the computational experiment on a computer are developed to predict the process of heat and moisture transfer in porous media, taking into account such factors as the internal heat and moisture release of a porous natural product on the example of raw cotton and its products of hulling, seeds of various crops. It also considers the effect of temperature and moisture content changes in the environment on the storage and drying of porous materials. In this study, the developed mathematical support of the object under research makes it possible to predict the change in temperature and moisture content at arbitrary points of the porous body and serves to prevent the loss of quality and spontaneous combustion of materials under solar radiation and to analyze and make managerial decisions. Based on the method of coordinate-wise splitting, a numerical algorithm for calculating three-dimensional heat and moisture transfer problems in areas of the parallelepiped type is presented. An implicit second-order difference scheme for calculating the required functions is presented. Based on the numerical calculations performed, it was established that moisture and heat transfer and their exchange with the environment occurs in the upper layers of the cotton pile; in the inner layers, there is an increase in temperature and moisture due to the respiration of raw cotton and its seeds, which depends on the degree of moisture of the raw cotton and their products of hulling.

The Influence of Heat and Moisture Transfer in Soil on the Performance of the Ground Heat Exchanger

2012 ◽  
Vol 594-597 ◽  
pp. 2120-2127
Author(s):  
Guo Min Shen ◽  
Chun Fang Lu ◽  
Yi Wang
Keyword(s):  
Thermal Properties ◽  
Heat Exchanger ◽  
Moisture Content ◽  
Moisture Transfer ◽  
Initial Moisture Content ◽  
Borehole Wall ◽  
Ground Heat Exchanger ◽  
Heat And Moisture Transfer ◽  
Soil Thermal Properties ◽  
Heat And Moisture

In this paper, a numerical heat and moisture transfer model (HMTM) and a pure conduction model (PCM) were established separately for unsaturated soil around the ground heat exchanger (GHE) and were numerically solved by finite volume method. The simulation results indicate that rejecting heat into soil can reduce moisture content in the vicinity of the borehole wall. When the initial moisture content is high, moister transfer has little effect on soil thermal properties. In this case, the results of the HMTM and the PCM are basically identical. On the contrary, when the initial moisture content is low, the thermal effect has significant influence on moisture transfer around the borehole wall, and the soil thermal properties will change correspondingly. In this case, there is a large difference between the results of these two models.

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.

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