The Thermal Diffusivity of Biochar Coating Deposited on a Heat Exchanger †

Biochar is a charcoal-like material obtained by burning organic wastes, coming from agricultural and forestry, in a controlled pyrolysis process. In this application, it is deposited on an aluminum foil of thickness 100 μm, which is used as a part of an heat exchanger. The thickness of the deposition of biochar on the aluminum foil ranges from 75 to 250 μm. The result coating is rough and, therefore, it is supposed to improve the heat exchange with the ambient environment, depending on the granulometry of the deposit. One key feature of the deposit is its thermal conductivity. In this work, it is determined by means of IR thermography used as a detector in a Laser Flash configuration. This allows us to evaluate the out-of-plane thermal diffusivity. Such measurements are complemented by density obtained by hydrostatic balance and specific heat by a differential scanning calorimeter.