The present study investigates the impact of different HCCI percentages on key engine parameters such as brake thermal efficiency (BTE), volumetric efficiency, exhaust gas temperature (EGT), and gaseous emissions, including NOX, HC, and CO. A data acquisition unit (DAU) was used to control the auto-ignition timing of the HCCI mode, ensuring precise and consistent combustion at different operating conditions. The results suggest that 20% HCCI offers the best trade-off of performance and emissions, achieving high brake thermal efficiency (BTE) with minimal HC and CO emissions. Higher HCCI percentages lower BTE and volumetric efficiency due to reduced combustion temperatures and intake air displacement, while NOX emissions significantly decrease at 60%-80% HCCI, though HC and CO emissions rise beyond 40% due to incomplete combustion. CO2 emissions increase with load but decline at higher HCCI levels, whereas O2 emissions remain largely stable. HCCI technology presents a promising pathway for cleaner and more efficient engines, supporting sustainable transportation with continued refinement. Received: 4 April 2025; Accepted: 22 May 2025
Kumar et al. (Thu,) studied this question.