Effect of grinding on thermal properties of wheat grain

Abstract

The aim of this study was to compare the thermal conductivity, thermal resistivity, volumetric heat capacity and thermal diffusivity of whole and ground wheat grain. The bulk density of whole grain ranged from 0.758 to 0.828 g cm⁻¹ (mean 0.806 g cm⁻¹), gappiness ranged from 37.7 to 40.2% (mean 38.5%), length ranged from 5.99 to 7.23 mm (mean 6.54 mm) and width ranged from 3.32 to 3.89 mm (mean 3.53 mm). In whole grain, the thermal conductivity (0.125–0.174 W m⁻¹ K⁻¹), volumetric heat capacity (1.366–1.767 MJ m⁻³ K⁻¹), thermal resistivity (6.058–7.893 m K W⁻¹), and thermal diffusivity (0.091–0.101 mm² s⁻¹) differed significantly from the ground wheat grain (size of 0.2 mm) characterised by the thermal conductivity that ranged from 0.096 to 0.119 W m⁻¹ K⁻¹, volumetric heat capacity ranged from 0.992 to 1.179 MJ m⁻³ K⁻¹, thermal resistivity ranged from 8.411 to 10.501 m K W⁻¹, and thermal diffusivity 0.093 to 0.105 mm² s⁻¹, respectively.