Soot Emission Reduction in a Biogas-DME Hybrid Dual-Fuel Engine

Bui Van Ga,Pham Quoc Thai

doi:10.3390/app10103416

Abstract

Combustion characteristics and harmful emissions with emphasized soot emission in the new concept of a biogas-dimethyl ether (DME) hybrid dual-fuel engine were analyzed. The effects of DME content, biogas compositions and diesel injection were examined. At any biogas composition, a rise in DME content in the fuel mixture leads to an increase in indicative engine cycle work (Wi) and NOx but a decrease in CO and soot volume fraction (fv). The effects of DME on Wi and soot volume fraction are more significant for poor biogas than for rich biogas, contrary to its effect tendency on CO and NOx concentrations. With a given operating condition and DME content, the biogas compositions slightly affect the performance and emission of a biogas-DME hybrid dual-fuel engine. At a fixed global equivalence ratio, the reduction of diesel injection leads to an increase in Wi and NOx concentration but a decrease in CO and soot volume fraction. The lower the diesel injection is, the more significant the effects of DME content on the combustion properties and pollutant emissions are. At a given operating condition and the same global equivalence ratio, the biogas-DME PCCI combustion mode is more advantageous than biogas-DME dual-fuel combustion mode. The substitution of diesel pilot ignition by DME pilot ignition in a biogas-DME hybrid dual engine is the optimal solution for both performance improvement and pollution emissions reduction.

Highlights

Despite relentless attempts to introduce electricity to the transport sector, internal combustion engines (ICE) remains the main vehicle propulsion in the upcoming decades
After the closure of the intake valve, the amount of fuel and air introduced into the cylinder was unchanged; the global equivalence ratio of the mixture remained stable until the starting of diesel injection for ignition (Figure 2b)
dimethyl ether (DME) content increased, Wi and NOx increased while CO and soot volume fraction decreased

Summary

Introduction

Despite relentless attempts to introduce electricity to the transport sector, internal combustion engines (ICE) remains the main vehicle propulsion in the upcoming decades. They will undergo further development of technologies for controlling soot and NOx emissions [1]. It is expected that dual-fuel mode offers a better way to control the combustion than the conventional diesel CI engine. This is due to the combustion characteristics of a fuel blend–air mixture that strongly depend on the fuel vaporization, the fuel–air mixing process, and the fuel chemical reactivity of each component [9,10,11]

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