Numerical validation of a method determining thermal diffusivity based on a measurement of a temperature profile

Abstract

The knowledge of dynamic thermal properties of building elements is necessary to investigate temperature and heat flux changes in natural daily and annual cycles. The basic dynamic parameter is thermal diffusivity. A method for determining its value for real objects has been proposed. This method is based on measuring the temperature in the element’s volume and on assuming that the obtained results meet the Fourier equation. Validation by a numerical experiment was made. The wall of the building with known thermal parameters was assumed and the temperature distribution was calculated over time in the process of non-stationary heat exchange. From the results, the diffusivity value was calculated and compared with the data entered into the model. Validations were performed for several accuracy of the temperature value and for two forms of function which approximated the temperature values obtained from calculation. A preliminary analysis of errors has been carried out. Keywords: measurements of thermal diffusivity, temperature distribution in a building element, approximation, heat transfer