Enhancement of combustion performance in renewable fuels engine: An experimental and numerical investigation on influence of fuel supply strategy for oxyhydrogen/bio-isopropanol/gasoline combined supply system

Amid the escalating global energy crunch, the sustainable clean energy is a core development direction for power systems. This study employs a combined experimental and numerical analysis approach to systematically investigate the effects of fuel supply strategies on combustion performance for an engine utilizing a ternary-fuel combined supply system consisting of “oxyhydrogen negative pressure inhalation + bio-isopropanol direct injection + and gasoline port injection” (ONPI + BIDI + GPI). The numerical analysis indicates that increasing the oxyhydrogen blend ratio enhances the peak concentrations of key radicals (OH, HO2, HCO) and intermediate products (H2O2, CO), optimizes the OH distribution in the cylinder, and raises the temperature in the cylinder. This explains the experimental observation that ONPI significantly improves engine combustion performance. Bench test results indicate that when the bio-isopropanol direct injection timing (BIDIT) is set in the intake stroke, HRR, Pmax, and combustion process parameters of the engine are significantly better than when set during the compression stroke. The engine's HRR, Pmax, IMEP, combustion process parameters, and CoVIMEP all improved with an appropriate increase in bio-isopropanol direct injection pressure (BIDIP), but excessively high BIDIP actually deteriorated the in-cylinder combustion environment. Notably, the coupled optimization of ONPI and BIDIT can enhance the power performance and combustion process of engines. Finally, this paper proposes “ONPIv = 16 L/min +250 °C A BTDC ≤ BIDIT ≤300 °C A BTDC + BIDIP = 9 MPa” as a feasible fuel supply strategy for improving the combustion performance of the system under the test conditions.