LAUSR

Abstract Recently, more attention has been paid to the application of biobutanol in spark ignition (SI) engines due to its superior properties among the biofuels. However, the high energy consumption and low efficiency of recovering biobutanol from ABE solution during the fermentation process lead to the high price of biobutanol, which limits its popularization in vehicles. Using ABE directly can solve the problem of high price of bio-butanol. This research explored the performance of an SI engine with ABE port injection (ABEPI) plus gasoline direct injection (GDI) at different excess air ratio (λ = 0.9, 1.0, 1.1, 1.2) and ABE port injection ratio (ABEPIr = 0, 25%, 50%, 75%, 100%). The results show that CA10-90 declines with increasing ABEPIr. CA0-10 and CA0-90 decrease with ABEPIr increasing at λ = 0.9, and first descend and then rise at λ = 1.0, 1.1 and 1.2. The coefficient of variations of IMEP (CoVIMEP) reaches the minimum value at ABEPIr = 75%. As ABEPIr increases, the peak in-cylinder pressure (Pmax), indicated mean effective pressure (IMEP) and brake thermal efficiency (BTE) increase at λ = 0.9 while first increase and then decrease at λ = 1.0, 1.1 and 1.2, reaching the maximum values at ABEPIr = 75%. Hydrocarbon (HC) reaches the minimum value at ABEPIr = 50%. Particle number decreases dramatically as ABEPIr increases from 0% to 50% and remains at an extremely low level when ABEPIr is greater than 50%. In summary, ABE is suitable for SI engine as an alternative fuel and fuels with high ABE ratio (≥50%) can effectively improve the combustion and particle emissions by ABEPI + GDI combined injection.