Dimensionless formulation and similarity to assess the main phenomena of heat and mass transfer in building porous material

Abstract

Within the environmental context, several tools based on simulations have been proposed to analyze the physical phenomena of heat and mass transfer in porous materials. However, it is still an open challenge to propose tools that do not require to perform computations to catch the dominant processes. Thus, this article proposes to explore advantages of using a dimensionless analysis by scaling the governing equations of heat and mass transfer. Proposed methodology introduces dimensionless numbers and their nonlinear distortions. The relevant investigation enables to enhance the preponderant phenomena to (i) compare different categories of materials, (ii) evaluate the competition between heat and mass transfer for each material or (iii) describe the transfer in multi-layered wall configurations. It also permits to define hygrothermal kinetic, geometric and dynamic similarities among different physical materials. Equivalent systems can be characterized in the framework of experimental or wall designs. Three cases are presented for similarity studies in terms of (i) equivalent material length, (ii) time of heat and mass transfer and (iii) experimental configurations. All these advantages are illustrated in the given article considering 49 building materials separated in 7 categories.