What question did this study set out to answer?

This study aims to evaluate how varying percentages of HCCI impact the performance and emissions from an engine fueled with compressed natural gas.

May 29, 2026

Performance and emission analysis of a homogeneous charge compression ignition engine fuelled with compressed natural gas

Key Points

This study aims to evaluate how varying percentages of HCCI impact the performance and emissions from an engine fueled with compressed natural gas.
Investigated various HCCI percentages (20% to 80%) on engine parameters like BTE, EGT, and emissions.
Employed a data acquisition unit for precise control of auto-ignition timing during combustion.
Analyzed the relationship between HCCI percentages and combustion efficiency under different operating conditions.
At 20% HCCI, optimal performance was achieved with high BTE and lower emissions of HC and CO.
NOX emissions decreased significantly at 60%-80% HCCI, while HC and CO emissions increased beyond 40% due to incomplete combustion.
CO2 emissions increased with load but decreased at higher HCCI levels, and O2 emissions remained stable.

Abstract

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

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