Effect of Season and Moisture Content on the Efficiency of Energy Consumption during Grinding and Various Physical Parameters of Wheat

Throughputs and power requirements for wheat using different hammer mill screen sizes were determined in a size reduction process. Physical properties of grinds such as modulus of uniformity, modulus of fineness, particle size, number of particles and surface area per gram of ground samples were determined. The mass of grains ground per unit time was used to calculate the throughput. Wheat grains at three moisture levels in three seasons were ground using a hammer mill with five different screen sizes (2, 3, 4, 5 and 6 mm). Among the three seasons studied, electricity and time consumption (minutes/quintal) was significantly low (P<0.05) in summer season compared to rainy and winter season. Energy consumption and time consumption (1.201kWh q–¹ and 5.14 m q–¹) were highest in rainy season, and least (0.439 kW h q–¹ and 3.39 m q–¹) in summer season with 2 mm screen size. The energy consumption was 263%, 715%, 1025% and 1730% more as the screen size decreased from 3 to 2, 4 to 2, 5 to 2 and 6 to 2mm. The screen size affected (P<0.05) the time consumption/throughput. As the screen size increased the modulus of fineness also increased. The modulus of uniformity (indicative of distribution of particles in coarse, medium and fine mesh screens, respectively) ranged from 0:8:2 to 4:6:0 in winter season, 0:8:2 to 5:5:0 in summer season and 0:8:2 to 7:3:0 in rainy season as the screen size increased from 2 to 6mm.The bulk density of wheat varied (P<0.05) from 702 to 768 kg m⁻³. The thousand grain mass of the grains increased linearly from 12.96±1.13 to 13.65 ±1.21g (P<0.05) as the moisture content increased from 8.63% to 12.60%. Number of particles per gram of sample decreased (P<0.05) in general with the increase of screen hole size and moisture level. The surface area (cm²/g) decreased (P<0.05) linearly from 60.73 to 28.18 with the increase of screen size from 2 to 6mm.