Effects of hydrogen assisted combustion of EBNOL IN SI engines under variable compression ratio and ignition timing

Alcohols are oxygenated fuels, holding a good reputation among alternatives, but single alcohol does not possess all qualities. Besides, the high latent heat and low vapor pressure limit their uses in SI engines. Hence, an energy enhancing and combustion promoting fuel helps overcome the drawbacks, among all available hydrogen fits the race most. Hence, hydrogen-assisted combustion of equivolume blend of ethanol/butanol (ENBOL) is experimentally tested under various compression ratios (CR) (11-15), ignition timing (16 degrees C A-24 degrees C A BTDC) for three hydrogen fractions (5%-15%) at three speeds (1400RPM-1800RPM). The experimental outcome notices an increase in brake power (BP), brake thermal efficiency (BTE), peak pressure (P-max), heat release rate (HRRmax), and NOx emissions with increasing CR and Hydrogen addition. The combustion duration, CO, and UBHC emissions reduce while CO2 emissions reduce with hydrogen; increasing CR notices a drop in CO2 at a much advanced or much-delayed ignition. Hydrogen improves combustion but reduces volumetric efficiency; increasing CR improves it, and hydrogen effect reduces with increasing CR. BP, BTE, and CA10-90 improve with retarding ignition from 24 degrees CA, while CA10, P-max, and HRRmax reduce continuously. UBHC and CO emissions increase while NOx reduces with retarding ignition. The ignition timing of 20 degrees CA at CR15 and 15% hydrogen performed better than gasoline. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study experimentally investigated the effects of hydrogen-assisted combustion of an equivolume blend of ethanol/butanol (ENBOL) under different compression ratios, ignition timing, and hydrogen fractions. The results showed that increasing the compression ratio and hydrogen addition improved combustion performance but reduced volumetric efficiency. Retarding ignition timing improved brake power and brake thermal efficiency but resulted in lower peak pressure and heat release rate, as well as increased CO and UBHC emissions.