Moisture dependent thermal properties of cassia

Abstract

Thermal and mechanical properties of cassia are primarily required in the study of its different thermal and mechanical operations. The thermal properties of cassia bark viz., specific heat, glass transition temperature (Tg), bulk thermal conductivity, and bulk thermal diffusivity were determined for a moisture range of 8–14% dry basis (d.b). Compression test was performed by Universal Testing Machine to examine the breaking characteristics of cassia along its three orthogonal directions at 11.10% d.b. moisture level. Results revealed that the specific heat increased from 1,553.12 to 3,232.90 J kg−1 °C−1 with an increase in moisture at 30°C. Whereas Tg decreased linearly from −66.67 to −86.09°C and the bulk thermal conductivity increased linearly from 0.10 to 0.14 W m−1 °C−1 with a rise in moisture content of the sample. Moreover, the bulk thermal diffusivity of cassia bark decreased from 2.75 × 10−7 to 1.62 × 10−7 m2 s−1 with an increase in moisture level. The average rupture forces for cassia bark through the minor axis, major and intermediate axis were 0.130, 0.123 and 0.109 kN, respectively, and corresponding average deformations at rupture were 1.36, 1.30 and 0.91 mm, respectively. In conclusion, the thermal properties of cassia were significantly affected by the variation in the moisture level. Also, the mechanical properties such as rupture force and rupture deformation demonstrated a prominent difference in their values along the three axes of the sample.

Keywords

• cassia
• specific heat
• glass transition temperature
• bulk thermal conductivity
• rupture force