Investigation of ignition characteristics and performance of a neat n-butanol direct injection compression ignition engine at low load. (15th November 2017)

• Record Type: Journal Article
• Authors: Yanai, Tadanori; Bryden, Geraint; Dev, Shouvik; Reader, Graham T; Zheng, Ming
• Is Part Of: Fuel. Volume 208(2017)
• Page Start: 137
• Page End: 148
• Publication Date: 2017-11-15
• Subjects: ATDC after top dead center -- BDC bottom dead center -- CA crank angle [°] -- CA5 the crank angle at 5% of mass fraction burned [°ATDC] -- CA50 the crank angle at 50% of mass fraction burned [°ATDC] -- CA95 the crank angle at 95% of mass fraction burned [°ATDC] -- CLD chemiluminescence detector -- CO carbon monoxide -- CO2 carbon dioxide -- COVimep coefficient of variation of IMEP [%] -- DI direct injection -- dp/dΘmax maximum cylinder pressure rise rate [bar/°CA] -- EGR exhaust gas recirculation -- FID flame ionization detector -- FFT fast Fourier transform -- FTIR Fourier transform infrared spectroscopy -- HCHO formaldehyde -- IMEP indicated mean effective pressure [bar] -- LHV lower heating value [MJ/L] -- msec millisecond -- Ne engine speed [rpm] -- NDIR non-dispersive infrared -- NOx nitrogen oxides -- O2 oxygen -- pinj injection pressure [bar] -- pmax maximum cylinder pressure [bar] -- PFI port fuel injection -- PMA paramagnetic analyzer -- TDC top dead center -- THC total hydrocarbons -- Φ equivalence ratio; Neat n-butanol -- Compression ignition engine -- Ignition -- Combustion -- Emissions -- Chemical kinetics simulation; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2017.06.096
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Neat n-butanol ignition characteristics in a direct injection CI engine were discussed. Chemical kinetic simulations were conducted to analyze the ignition characteristics. The combustion and emission characteristics at low load were discussed. Abstract: Neat (100%) n-butanol was implemented in a direct injection (DI) compression ignition (CI) engine. The ignition, combustion, and emission characteristics at low engine load (below 6.5 bar IMEP), including near idling, were investigated. The engine experiments were performed using a modern common rail type single cylinder DI CI engine with a compression ratio of 18.2:1. Chemical kinetic simulations were also conducted to analyze the ignition characteristics of the experiments. The research results showed that neat n-butanol could not be auto-ignited at normal intake temperature and pressure conditions due to its low reactivity. However, the use of a high intake pressure of 0.75 bar gauge, and an injection timing of −26° ATDC at 5.0 bar IMEP, enabled auto-ignition even without the use of intake heating. One possible reason for this was attributed to the enhancement of the low temperature reaction regime. The ignition timing advancement sensitivity to intake pressure was approximately 1.0 °CA/0.1 bar at 5.0 bar IMEP, and a higher intake pressure allowed a wider injection timing range. A neat n-butanol fueled DI CI engine had a five times longer ignition delay and a 85% longer combustion duration than the same engine fueled with diesel at 2.0 bar IMEP. However, the combustion duration tended to shorten rapidly with increasing engine load, which was the opposite tendency to diesel. At low load, the nitrogen oxides (NOx) and soot emissions were very low compared to those of diesel, whereas the total hydrocarbons (THC), formaldehyde (HCHO), and carbon monoxide (CO) were higher than those of diesel. Carbon dioxide (CO2 ) emission was lower than that of diesel. This could be due to the reduced CO oxidation and the lower carbon content in n-butanol. Finally, by combining the previously published results with these results in this research, fuel injection strategies and intake oxygen conditions required to achieve low NOx (≤0.60 g/kWh) and soot (≤0.02 g/kWh) emissions and moderated maximum cylinder pressure rise rate (≤10 bar/°CA) were summarized over a wide load range of 2.0–11.5 bar IMEP.