Effect of oxygen flow rate on temperature and pressure distribution in a motorcycle exhaust system with activated candlenut shell adsorbent

This study investigates the thermofluid behavior of a motorcycle exhaust gas treatment system incorporating activated charcoal derived from candlenut (Aleurites moluccanus) shells, with and without supplementary oxygen injection. A modified exhaust casing was designed to house the adsorbent and was equipped with pressure and temperature sensors at multiple points. The system's performance was evaluated under varying oxygen flow rates (0, 1, 2, and 3 L/min), focusing on pressure differentials and temperature distributions during steady-state engine operation. Results showed that the inclusion of activated charcoal significantly increased the pressure drop across the adsorbent bed, indicating effective interaction between the exhaust gases and the porous medium. However, as the oxygen flow rate increased, the pressure differential decreased, suggesting improved flow permeability and reduced adsorbent clogging. Simultaneously, the internal temperature of the casing rose with higher oxygen levels due to exothermic oxidation reactions, particularly in the middle and rear sections of the adsorbent. These findings highlight the dual role of oxygen in enhancing pollutant removal and maintaining optimal thermal and flow conditions within the adsorbent system. The study contributes critical insights for the design and optimization of low-cost, biomass-based emission control technologies for small-displacement engines in resource-limited settings.