Effects of equal spark timing on performance emission and combustion characteristics of SI engine using hydrogen and CNG blends

Abstract

This paper shows the effects of equal spark timing on hydrogen enriched compressed natural gas (HCNG) fuel blends for three cylinder SI engine using sequential port fuel injection system. All trial are performed at fixed compression ratio of 9.2 with varying fuel blends of 0, 5, 10 and 15 % hydrogen by energy with CNG at wide open throttle (WOT) position. Equal spark timing (EST) shows reduction in power output with increase in NO x emission compared to maximum brake torque (MBT) spark timing for all fuel blends. Brake thermal efficiency reduced from 23.08 % for MBT spark timing to 17.94 % for EST at 2500 rpm. Spark timing is kept constant for all fuels blends, in order to assess their interchangeability on SI engine. The maximum peak pressure for 5 % hydrogen addition is observed to be 29.36 bar occurred at 24°ATDC. At lean condition COVIMEP and heat release rate increased with EST compared to MBT spark timing.