The effect of moisture content on the thermal properties of sunflower seeds. (Helianthus annuus L.)

Abstract

Heat transfer in oil seeds is an important issue during production and in handling and processing. Since oil seeds are heat-sensitive due to their composition, their quality may suffer if they are exposed to excessive heat. In some cases heat transfer is also accompanied by mass transfer such as drying or dehydration. In this research in addition to thermal properties namely thermal conductivity, thermal resistance, specific heat capacity, enthalpy, thermal diffusivity values; some physical properties such as dimensional properties, geometric mean diameter, sphericity, bulk density and 1000 seeds weight were determined experimentally. Also water activity values were measured by using a water activity measurement device. All measurements were performed for three different moisture level namely 5.78, 1618, and 24.2 % (w.b.). The thermal conductivity and thermal resistance were measured by KD2 device that is working according to the transient technique using a line heat source. The specific heat capacity was measured by a calorimeter. Thermal diffusivity was calculated by using obtained data. Enthalpy and water activity values were measured by using a special apparatus that works with Testo 650 data logger. Except thermal resistance all thermal properties increased as the moisture content increased.