A Model for Assessment of Heat and Moisture Transfer Hollow a Hemp Concerte Wall Using Finite Element Method

The energy performance of buildings represents a major challenge in terms of sustainable development. The buildings and buildings construction sectors combined are responsible for over one-third of global final energy consumption and nearly 40% of total direct and indirect CO2 emissions. In order to reduce the energy consumption of buildings and their harmful impact on the environment, special attention has been paid in recent years to the use of bio-based materials. In the present paper, a model of heat and moisture transfer hollow hemp concrete wall is proposed using finite element method. The energy and mass balances are expressed using measurable transfer drivers as temperature water content and vapor pressure and coefficients related explicitly to the macroscopic properties of material as thermal conductivity, specific heat, and water vapor permeability. The proposed model is implemented in MATLAB code and validated through experimental measurements.

Verification of the model for calculating conjugated heat and moisture transfer when moistening porous material

This paper presents a mathematical model used to calculate conjugated heat and moisture transfer in porous building materials. The initial region of the sorption isotherm for a given material was reconstructed based on the experimental data on moisture transfer in aerated concrete. The calculation results are compared with the experimental data on porous material moistening under different heat and moisture conditions. The calculations performed confirmed that model works well for sorption moistening, and not quite well with capillary impregnation. This does not exclude the possibility of engineering calculations using this model; however, at over-hygroscopic region their accuracy is not quite high.

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

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.

Development of a numerical approach to assess the effect of coupled heat and moisture transfer on energy consumption of residential buildings in Moroccan context

Hygrothermal properties of building materials, climatic conditions and energy performance are interrelated and have to be considered simultaneously as part of an optimised building design. In this paper, a new approach to evaluate the energy consumption of residential buildings in Morocco is presented. This approach is based on the effect of coupled heat and moisture transfer in typical residential buildings and on their responses to the varied climatic conditions encountered in the country. This approach allows us to evaluate with better accuracy the response of building energy performance and the indoor comfort of building occupants. Annual energy consumption, cooling and heating energy requirements were estimated considering the six climatic zones of Morocco. Based on the results, terms related to coupled heat and moisture transfer can effectively correct the existing energy consumption calculations of the six zones of Morocco, which currently do not consider energy consumption due to coupled heat and moisture transfer.