PHYSICAL AND THERMAL PROPERTIES OF EUCALYPTUS WOOD CHARCOAL.

ABSTRACT

The knowledge of the physical and thermal properties of eucalyptus charcoal is of fundamental importance in the design of equipment and development of cooling technologies. However, literature about physical properties for eucalyptus wood charcoal is largely unavailable, especially the thermal and aerodynamic properties, for the same material. The aim of this study was to evaluate the physical properties of eucalyptus charcoal: apparent and bulk density, pressure drop, porosity, thermal conductivity and specific heat to support the design of production and cooling systems using heat exchangers. It was found that the pressure drop could be expressed according Forchheimer’s law and logarithmical empirical models, resulting in R² above 0.95. The apparent and bulk densities were measured as 344.6 ± 17.6 and 155.3 ± 4.1 kg.m^-3, respectively, and the charcoal porosity was 54.8 ± 2%. In the investigation of flow in porous charcoal media, the pressure gradient is proportional to the increase of the superficial airflow velocity and is dependent on the charcoal bed height for low airflows and lower bed heights. However, the gradient was independent of bed height on all tests with columns larger or equal to 0.80 m. The thermal conductivity and specific heat were 0.030 ± 0.0027 W m^-1.K^-1 and 1017 ± 74 J.kg^-1.K^-1, respectively.

Keywords:
Kiln; Porosity; Pressure drop; Specific heat; Thermal conductivity