The effects of the air-fuel ratio on a stationary diesel engine under dual-fuel conditions and multi-objective optimization

Jungkeun Cho, Sangjun Park and Soonho Song

Energy, 2019, vol. 187, issue C

Abstract: The fundamental combustion characteristics and engine performance of a dual-fuel engine, fueled with diesel and natural gas, were investigated using a commercial 1D simulation program (GT-Power). Furthermore, the effects of air-fuel ratio under dual-fuel combustion conditions were studied, and optimized design points that minimize brake-specific fuel consumption (BSFC) and nitrogen oxides (NOX) emissions simultaneously were determined using a multi-objective Pareto optimization method. The engine model was validated based on experimental results and previous work under various engine loads. The thermal efficiency of the engine, which was modified from a diesel to a dual-fuel engine, showed a decreasing tendency as the natural gas substitution ratio (NSR) increased due to changes in the combustion characteristics. The decline in thermal efficiency in dual-fuel combustion could be improved somewhat by optimizing the injection strategy. Under dual-fuel combustion conditions, an optimum air-fuel ratio value for BSFC could be determined, especially for higher NSR conditions. However, NOX emissions showed a tendency to increase with increasing air-fuel ratio. The relationship between the trends was more than a simple tradeoff, so multi-objective Pareto optimization was conducted to minimize both BSFC and NOX emissions, with start of injection timing and air-fuel ratio as variables. Ultimately, optimal design points were determined.

Keywords: Air-fuel ratio; Combustion characteristics; Diesel; Dual fuel; Natural gas; Pareto multi-objective optimization (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:187:y:2019:i:c:s0360544219315567

DOI: 10.1016/j.energy.2019.115884

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