Abstract
In this paper, a four-stroke engine diesel was employed to investigate the effects of different fuel mixture ratios of diesel and ethanol on engine performance and emission characteristics in terms of cylinder temperature, heat release rate, brake power, brake thermal efficiency, brake specific fuel consumption, and cylinder pressure. The corresponding simulation model of diesel engine was developed by AVL-Fire coupled CHEMKIN code, and an improved chemical kinetics mechanism containing 34 reactions and 19 species was employed to simulate the fuel spray process and combustion process. The simulation model was validated by experimental results under 100% and 50% load conditions and used to simulate the combustion process of diesel engine fueled with pure diesel and diesel–ethanol blends with 10%, 20%, and 30% ethanol by volume, respectively. The results showed that the increase of ethanol content in the blended fuel had a certain negative impact on the performance characteristic of diesel engine and significantly improved the emission characteristic of the engine. With the ethanol proportion in the blended fuel increased to 10%, 20%, and 30%, the brake thermal efficiency of the engine increased by 2.24%, 4.33%, and 6.37% respectively. However, the brake-specific fuel consumption increased by 1.56%, 3.49%, and 5.74% and the power decreased by 1.58%, 3.46%, and 5.54% respectively. In addition, with the ethanol proportion in the blended fuel increased to 10%, 20%, and 30%, the carbon monoxide emission decreased by 34.69%, 47.60%, and 56.58%, and the soot emission decreased by 7.83%, 15.24%, and 22.52% respectively. Finally, based on the combining fuzzy and grey correlation theory, nitrogen oxide emission has the highest correlation with engine power and brake-specific fuel consumption. The values reach 0.9103 and 0.8945 respectively. It shows that nitrogen oxide emission and cylinder pressure have a significant relationship on engine power and brake-specific fuel consumption.
Highlights
The nitrogen oxides (NOx) emission of diesel engine accounts for 70% of the total vehicle emission [6], which is the main pollution source leading to the formations of acid rain and chemical smog
The results showed that with the increase of ethanol content in the blended fuel, the emissions of carbon monoxide (CO) and smoke were reduced by 44% and 38% respectively
The influences of different fuel ratios on engine performance and emission characteristics were studied in terms of brake power, brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), cylinder temperature, NOx emission, CO emission, soot emission, HC
Summary
The results showed that with the increase of ethanol content in the blended fuel, the emissions of carbon monoxide (CO) and smoke were reduced by 44% and 38% respectively. This showed that the addition of ethanol could improve the emission characteristic of the engine. The use of diesel–ethanol blended fuel can significantly improve the emission characteristic and effectively reduce the pollutant emission. The AVL-Fire software coupled with CHEMKIN code was used to develop the diesel engine model and investigate the effect of different ethanol ratios in blended fuel on the performance and emission characteristics of diesel engine.
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