Papers by Keyword: Moisture Transfer

Abstract: The knowledge of moisture transfer in multi-layered building materials and components using numerical simulations is fundamental to predict the behaviour of that building materials and components when in contact with moisture and to avoid some possible future pathology guarantying a correct performance.This paper describes a comparative analysis of experimental values of Hygric Permeance (HP) obtained by water absorption curves and gamma-ray attenuation profiles, for perfect contact interface. ARTICLE REVISED ON 25.03.2022

Abstract: After intensifying the knowledge of hygric permeance (HP) in multi-layered test samples, which were subjected to the imbibition process, a significant set of HP values (with different interface types) was experimentally achieved. This was done in order to develop a new model which allows estimating more correctly the hygric permeance. The idea is predicts the HP with several scenarios, i.e., different interfaces (perfect contact, hydraulic contact and air space interface), interfaces heights and materials studied, in the attempt to estimate the HP without the need to resort to the measurement by the experimental route in the attempt to estimate the HP without the need to resort to the measurement by the experimental route and even with possible measurement, generator automatic calculation (without human opinion/criteria). In this paper, the Hygric Permeance will be calculated by two different methods, gravimetric and gamma ray methods, and a new methodology proposes. The maximum flows transmitted were determined by the slope of the mass variation per contact area in function of the time involved. When having interface, the calculations admit that the first layer is saturated and that all the increased weight stems becomes from the relative humidity that penetrates the interface. The new methodology proposed is analysis of the prevision mathematical model that describes the mass variation per contact area in function of the time, after the “knee point”. This work it is the first attempt to provide a set of values that refer from hygric permeance in masonry of building walls, these being random values experimentally determined.

Abstract: The phenomena of transport in porous media arises in many diverse fields of science and engineering, ranging from agricultural, biomedical, building, ceramic, chemical, and petroleum engineering to food and soil science. Several authors provide an extensive description of the problems involving porous media. For building engineering, obtaining a good understanding of moisture transport in building envelopes is becoming one of the most important tasks. In the last few decades, many studies investigating moisture transport in building envelopes have been published, which have helped to improve overall building envelope design. This work presents a brief review of these studies.

Abstract: The paper discusses an experimental hygrothermal analysis of differently constructed additional mineral wool wall and attic insulation of a family house in Hajdúnánás, Hungary. The walls of the building were insulated in two different ways: half of the façade was insulated with Knauf stone mineral wool insulation boards glued to the walls in a continuous mortar bed as recommended, and on the other side of the same façade, the boards were glued only with patches of mortar. In the attic of the same building, one part of the attic was insulated by using Knauf glass mineral wool insulation batts along with vapour permeable underlay membrane as recommended, while the other part was constructed without underlay. Temperature and relative humidity sensors were placed between the layers and heat flux sensors were installed on the internal surfaces of the two differently constructed wall and attic insulations. An external meteorological station was installed on an unused chimney of the building. Besides the structural sensors, temperature and relative humidity sensors were installed in each room, and the energy consumption of the building was also monitored during the measurements. For control values, we monitored the internal hygrothermal conditions and the energy consumption of an identical but uninsulated family house only 8 km away in Hajdúdorog, Hungary. In the article, we analyze the heat and moisture transport through the building constructions and the energy consumption of the family house according to the recorded data of a full heating season.

Abstract: In this paper a conjugated heat and moisture transport investigation of industrial floors is presented. We have analyzed 2D general segments of wall and foundation connections in three different climatic conditions: Budapest (Hungary), Lisbon (Portugal) and Espoo (Finland). We also modeled the component with horizontal or vertical edge insulations with various thicknesses and lengths, and two different soil compositions under the floors. The design of the floor and wall components was performed according to the current standards. We examined 126 combination of the segment and the results shows difference both in relative humidity across the components and heat losses through the internal faces. In conclusion, the simulations and results can improve the energy efficient design of industrial buildings across Europe.

Abstract: One of the strategic goals of Europe 2020 is the reduction of greenhouse gas emissions by 20 % by 2020 compared to year 1990 and increasing energy efficiency by 20 %. Closely related to the revitalization of structures necessary for reasons reduction of their unsatisfactory energy consumption and then also the construction of new building structures with minimal energy requirements by using less energy demanding materials, if is it possible from easily renewable resources. Currently, the structures involved a high degree of total energy consumption in the European Union, about 40 %. Thermal insulating plasters with using lightweight aggregate based on recycled glass are the appropriate remediation materials for the rehabilitation of existing buildings, or even for thermal insulation of new structures. In view of the fact that historic buildings are often exposed to dampness and moisture, it is necessary for these redevelopment plasters also tackle studios moisture transport. The paper describes the results of the development of new insulating plasters that would have been reflected particularly in the rehabilitation of historic buildings and problematic details of building structures.

Abstract: This paper defines the hygrothermal material properties (thermal conductivity, density, specific heat capacity, vapor diffusion coefficient and resistance, moisture storage function, water absorption coefficient and liquid transport coefficient) of steel fiber reinforced concretes that are widely used for industrial floors, based on laboratory measurements. The measured and calculated material properties are necessary to carry out a dynamic heat and moisture simulation of a component or a building containing steel fiber reinforced concrete layers.

Abstract: In this article provides a reasoned justification for the use of weatherproof membranes from fiberglass in double skin facades according to the criteria for optimum design of heat and humidity regime. The experiment of membranes' flammability was carried out. The article presents the results of the membrane’s effect on the flow into double skin facades.

Abstract: The numerical-analytical solution of the non-axisymmetric problem of moisture-elasticity for hollow cylindrical soil massive is provided. We consider the steady-state water transfer. Inhomogeneity of the array due to the dependence of the deformation modulus on the soil moisture. Stress state of the array caused by forced deformations and uneven pressure rebuff of the soil. The method for solving non-axisymmetric problems with radial inhomogeneity in polar coordinates is described. Diagrams on the stress fields in homogeneous and inhomogeneous formulations of the problem are provided. In the paper made a comparative assessment of the impact on the stress state of the power factors and inhomogeneity of the soil

Abstract: The numerical-analytical solution of the axisymmetric problem of moisture-elasticity for hollow spherical soil massive is provided. We consider the steady-state water transfer. Inhomogeneity of the array due to the dependence of the deformation modulus on the soil moisture. Stress state of the array caused by forced deformations and uneven pressure rebuff of the soil. The method for solving non-axisymmetric problems with radial inhomogeneity in polar coordinates is described. Diagrams on the stress fields in homogeneous and inhomogeneous formulations of the problem are provided. It describes a method of calculating radial inhomogeneous axisymmetric problem of theory of elasticity for thick-walled spherical shell.