Solução da equação de condução de calor não estacionária em meios multicompostos

Abstract

The temperature, one of the main degradation factors active in facade coatings, is responsible for the cause of numerous behavior in the materials, thus causing, physical and chemical changes that may result in certain pathologies. The behavior of these coatings when subjected to inclement weather are reflected directly in the thermal behavior of the building internal environments, interfering on important aspects such as thermal comfort of users and air conditioning systems. Increasingly it is realize that a building project can not be reduced only to meet the security needs, aesthetics and comfort of users, but it is also necessary to create a favorable environment and the need for a study facing the main causes pathologies in construction systems. Propose then, in this work, a methodology capable of performing in a semi-analytical way the calculation of the existing heat flows in the envelope of the building, giving special attention to external walls composed of more than one layer. The distribution of temperatures in the layers are one-dimensional transient solutions of conduction of heat. Such solutions are obtained by the method of the Laplace transform method and numerical inversion for a wall composed of only one material. It will also be presented solutions for a wall composed two, four and n layers. For an analysis of the proposed model, we wil use thermo-physical properties found in the literature, and it is possible to perceive that the model represents satisfactorily the behavior of the materials studied. The model was first applied to simulate the heat transfer in a plate made up of two materials. In a second moment this formulation was applied composed of concrete and plaster, and finally a wall composed of four layers. The results obtained through the model are of great contribution to a more accurate evaluation of the non-stationary heat exchange in multilayer walls, presenting valid results to describe the temperature gradient and making possible the analysis at each point of the element.