Simple and inexpensive method of wood pellets macro-porosity measurement

Macro-porosity and bulk density are the properties of wood pellets that have great influence on the efficient storage and transportation systems designs and operations. Methods of measuring macro-porosity are either limited or use expensive instruments. A novel simplified stereometric measurement method for determining the macro-porosity of wood pellets through geometrical approach was successfully developed and tested. In the developed method, the irregular broken offends sanded flat so that the pellet geometry with the existing circular cross section becomes a cylinder, and the actual volume was evaluated from their dimensions using mensuration formula. Such formed cylindrical pellets of known volumes were loose or tapped filled to selected volumes to evaluate the macro-porosity and the constant specific weight, from which the actual wood pellets properties were evaluated. Mass measurements along with fill volumes evaluated the bulk density of wood pellets. Mean specific weight of cylindrical pellets was determined as 1133.9±13.6 kg/m³. Overall mean macro-porosities of actual wood pellets were 40.7±2.4% and 35.3±2.4% that were classified as "Medium" and "Medium to Low" for loose and tapped fills, respectively. The overall mean bulk densities of actual wood pellets were 672±27 kg/m³ for loose fill and 733±27 kg/m³ for tapped fill. Tapping produces a significant decrease in porosity (≈5%) and increase in density (≈60 kg/m³) that can be utilized advantageously for efficient wood pellets handling. The developed stereometric method can be used as a handy inexpensive laboratory procedure to estimate the macro-porosity of different types and makes of wood pellets and other similar packaged materials.