Investigation of the Mechanical and Thermal Properties of Briquettes Made from Pruning's of Date Palm (Phoenix dactylifera), Olive (Olea europaea), and Citrus Trees

Abstract

This study was conducted at the laboratories of the Faculties of Agriculture and Engineering at the University of Tripoli. It investigated several mechanical and thermal properties of compressed biochar units (briquettes) derived from palm, olive, and citrus byproducts. The biochar produced through pyrolysis was ground, and corn starch was added as a binding agent at concentrations of 6g and 10g per 90g of biochar representing 6.7% and 11.1%, respectively. The components were hand kneaded, and a metal mold with an inside diameter of 4cm and a pressing tool were used to form cylindrical units weighing approximately 22g. The samples were dried, and their moisture content and dry density were determined, followed by compression testing and the assessment of combustion characteristics.

The results revealed a significant effect of both the starch percentage and the species type on the studied properties. The highest dry density was recorded for palm biochar at 0.596 g/cm3, followed by olive at 0.570g/cm3, and then citrus at 0.5440g/cm3. Regarding compressive stress, the differences were also significant; palm recorded the highest strength at 1.71 MPa , followed by olive at 1.63 MPa , while citrus recorded the lowest value at 1.26 MPa.

The influence of the starch ratio and species type was also significant on combustion characteristics. Citrus biochar recorded the highest energy production rate at 1002.77 kJ/kg and a maximum water temperature of 85.65°C. This was followed by olive with an average of 916.13 kJ/kg and 80.07°C, while palm recorded 826.58 kJ/kg and 75.35°C. Additionally, palm biochar yielded the highest ash content at 3.47g, followed by olive at 2.02g, while citrus had the lowest amount at 1.95g. Overall, the study demonstrated the durability briquettes using a starch ratio of approximately 10%, and confirmed that these byproducts can be used as effective energy sources.