Mechanical Properties and Performance Characteristics of Shea Kernel–Groundnut Shell–Derived Bio‐Briquettes for Rural Energy Applications

The physicochemical, mechanical, and combustion properties of charred‐briquettes, made from shea kernel shell (SKS) and groundnut shell (GS), were studied for rural household applications in northern Ghana. The shells were carbonized through thermal pyrolysis and then mixed with a binder (cassava peel) to fabricate solid briquettes at varied material‐binder ratios of 90 wt%:10 wt%, 85 wt%:15 wt%, 80 wt%:20 wt%, and 75 wt%:25 wt% for optimization purposes. The briquette’s mechanical properties including compressed density ( D c ), relax density ( D r ), relaxation ratio ( R r ), shatter resistance index (SRI), water penetration resistance index (WPRI), as well as compressive and tensile strength tests were determined. The D c , D r , SRI, and WPRI for both materials’ briquettes largely increased as percentage binder content increased, whereas the R r decreased. The decreasing R r improves mechanical stability, while a high WPRI indicates effective heating; both parameters are desirable for quality briquette production. The compressive strength test reported in this work ranged from 392–682 N/mm 2 for SKS briquettes and 406–687 N/mm 2 for GS briquettes. Whilst the tensile strength test reported for SKS briquettes ranged from 275–422 N/mm 2 and 312–474 N/mm 2 for GS briquettes. The water boiling time recorded for SKS briquette samples was 38.4 min at a burning rate of 2.81 g/min, whilst GS briquettes recorded 43.5 min at 2.305 g/min burning rate, respectively. The calorific values for SKS and GS briquettes were 26.15 MJ/kg and 25.33 MJ/kg, while the thermal efficiencies recorded were 49% and 38%, respectively.