A Laboratory-Made Flash Apparatus to Simultaneously Estimate the Thermal Properties of Three Building Materials

Determination of thermophysical properties of construction materials such as lambda, Cp, and a, is essential to assess their thermal behavior in buildings. To measure these properties, several highly sensitive techniques exist. However, in addition to the length of time required, it remains difficult to make separate measurements in the same conditions of temperature, humidity, and sampling. In this paper, a procedure is presented to handle this problem. Therefore, thermal measurements are conducted using a laboratory transient flash apparatus made in agreement with the ASTM standard E1461-13. The heat pulse shape of the power generated by the apparatus was determined experimentally and the recorded data were then modeled using a script written in the Mathematica language. The numerical estimation procedure is then proposed to estimate simultaneously the diffusivity, conductivity, and specific capacity of three composite samples made of clay and straw. The good agreement in the difference between the estimated thermophysical properties and those measured separately using the required apparatus proves that the proposed procedure has reliable and reasonable accuracy. The maximum difference reached 7.41% for thermal conductivity and 5.70% for specific thermal capacity.