THERMAL PROPERTIES OF RADISH AND ALFALFA SEEDS

Thermal conductivity, specific heat, and density were measured in a temperature range of 30C to 80C, and moisture content of 4.6% to 6.5% for radish seeds, 5.0% to 7.3% for alfalfa seeds typically encountered in the radio frequency dielectric heating for seeds. Thermal conductivity and specific heat were determined using a linear heat source probe and a modified calorimeter method, respectively. Thermal conductivity of radish and alfalfa seeds ranged from 0.050 to 0.091 W/mC (SD: 0.011) and 0.075 to 0.120 W/mC (SD: 0.012), respectively. Specific heat was in the range of 0.290 to 0.479 kJ/kgC (SD: 0.051) for radish seeds and 0.333 to 0.593 kJ/kgC (SD: 0.076) for alfalfa seeds. Density of radish and alfalfa seeds ranged from 684 to 675 kg/m³ (SD: 5.592) and 819 to 804 kg/m³ (SD: 8.921), respectively. Thermal diffusivity of the seeds was also determined, and the values varied from 25.13 × 10^?8 to 34.47 × 10^?8 m²/s for radish seeds and 27.14 × 10^?8 to 29.73 × 10^?8 m²/s for alfalfa seeds. Regression models were fitted to the experimental data for each thermal property, and showed second order polynomial relationships with temperature and moisture content.