Thermal characterization of homogeneous walls using inverse method

Abstract Current environmental concerns have promoted efforts to reduce the consumption of energy. In moving towards improving existing buildings, the study of the thermal behaviour of a wall is not easy because its actual thermophysical properties are not well-known. These parameters are nevertheless fundamental for the economic optimisation of building refurbishment or for the verification of their performance in situ. It is thus important to be able to characterize existing building walls. The objective of our study was to develop a method to thermally characterize a wall adapted to in situ applications based on an active approach. The principle of identification consists of thermally examining an access surface by applying a heat flux and studying the response in terms of the temperature recorded by infrared thermography on the opposite surface. Based on signals of flux and of temperatures measured at the edges of the wall, the thermophysical properties (thermal conductivity and volumetric heat) of the wall are estimated by inverse method. The method was applied first to a homogeneous gypsum-tile panel in laboratory. The results were compared to reference values obtained from a classical procedure. Then, the method has been implemented in situ on a homogeneous reinforced concrete shell.

[1]  Vittorio Ferraro,et al.  A method for the experimental evaluation in situ of the wall conductance , 2006 .

[2]  Rossano Albatici,et al.  Infrared thermovision technique for the assessment of thermal transmittance value of opaque building elements on site , 2010 .

[3]  S. Chudzik.  Measurement of thermal diffusivity of insulating material using an artificial neural network , 2012 .

[4]  Oleg M. Alifanov,et al.  Analysis of Statements and Solution Methods for Inverse Heat Transfer Problems , 1994 .

[5]  Didier Defer,et al.  The characterization of thermophysical properties by thermal impedance measurements taken under random stimuli taking sensor-induced disturbance into account , 1998 .

[6]  O. Carpentier,et al.  Formalism of thermal waves applied to the characterization of materials thermal effusivity. , 2011, The Review of scientific instruments.

[7]  Changhai Peng,et al.  In situ measuring and evaluating the thermal resistance of building construction , 2008 .

[8]  D. Marquardt.  An Algorithm for Least-Squares Estimation of Nonlinear Parameters , 1963 .

[9]  Ermanno Grinzato.  State of the Art and Perspective of Infrared Thermography Applied to Building Science , 2012 .

[10]  Steven M. Shepard,et al.  Introduction to active thermography for non‐destructive evaluation , 1997 .

[11]  Michael Yit Lin Chew.  Assessing building façades using infra‐red thermography , 1998 .

[13]  Didier Defer,et al.  Thermal characteristics in situ monitoring of detached house wall constituted by raw clay , 2010 .

[14]  M. Chantant,et al.  Experimental thermal study of a solar wall of composite type , 1997 .

[15]  J. Gabano,et al.  Fractional modelling applied to heat conductivity and diffusivity estimation , 2009 .

[16]  R. J. Jenkins,et al.  Flash Method of Determining Thermal Diffusivity, Heat Capacity, and Thermal Conductivity , 1961 .

[17]  Kenneth Levenberg.  A METHOD FOR THE SOLUTION OF CERTAIN NON – LINEAR PROBLEMS IN LEAST SQUARES , 1944 .

[18]  Xavier Maldague,et al.  Theory and Practice of Infrared Technology for Nondestructive Testing , 2001 .

[19]  D. Leclercq,et al.  Apparatus for simultaneous temperature and heat‐flow measurements under transient conditions , 1983 .

[20]  O. Alifanov.  Inverse heat transfer problems , 1994 .

[21]  Olivier Carpentier,et al.  In situ thermal properties characterization using frequential methods , 2008 .

[22]  R. Zengerle,et al.  A micro dew point sensor with a thermal detection principle , 2012 .

[23]  Didier Defer,et al.  Measurement of low-thermal effusivity of building materials using thermal impedance method , 2001 .