DETERMINATION OF SELECTED ENGINEERING PROPERTIES OF NEEM SEED FOR PROCESS MACHINE DESIGN

Abstract

The physical, mechanical, aerodynamic and thermal properties of neem seed (Azadirachta indica) relevant to the development of a processing machine for the seed were determined in this study. These properties were determined in the moisture content range of 5.16–22.43% w.b. Axial dimensions of the seed were determined as a function of moisture content and results from the study showed that there is a linear relationship between the moisture content of the seed and the axial dimensions. The average length, width, thickness, geometric mean diameter, sphericity and surface area of the seed increased from 11.57 mm -12.01 mm, 4.38 mm-4.44 mm, 3.36 mm-3.74 mm, 5.42 mm- 5.82 mm, 0.47-0.49 and 92.85 mm2-106.97 mm2.The bulk density, true density and porosity of seed decreased with increase in moisture content from 664.460-386.554 kg/m3, 1155.903-515.902 kg/m3 and 25.072-42.516%. Angle of repose and thousand seed mass increased with the increase in moisture content from 20.20-33.20 and 132-172.2 g as the moisture level is varied from 5.16-22.43% w.b. The static coefficient of friction on plywood , galvanized iron ,mild steel, and glass surfaces increased from 0.48 -0.68, 0.44-0.57, 0.42-0.47 and 0.38 to 0.46 respectively. The terminal velocity of the seed ranged from 1.22-3.24 m/s. The mechanical property was investigated by using an Instron universal testing machine (model 3369). Compressive strength decreased with increase in moisture content from 3.43 – 9.97 N/mm2 as the moisture content decreases. Compressive strength of the neem seed increased from 3.13 to 8.60 N/mm2 as the moisture content decreased from 22.43 to 5.16% w.b under lateral loading and from 3.43 to 9.02 N/mm2 under axial loading. On the other hand and under longitudinal loading, the property increased with decrease in moisture content from 3.75 to 9.97 N/mm2. The Young modulus of elasticity increased with increase in the moisture content from 1.059 MPa to 5.24 MPa. The thermal conductivity of neem seed investigated increased linearly from 0.8-1.3 W/M/0C while the specific heat capacity increased from 0.89-3.55 KJ/Kg/0C as the moisture content increased from 5.16-22.43% w.b. The thermal diffusivity of seed ranged from 7.053E-07 to 1.16E-06 m/s. The data generated from this study are useful for the development of a process machine for the seed.