Effects of Fuel Injection Pressure on Combustion and Emission Characteristics under Low Speed Conditions in a Diesel Engine Fueled with Palm Oil Biodiesel

Ho Young Kim,Jun Cong Ge,Nag Jung Choi

doi:10.3390/en12173264

Abstract

In this study, the effect of injection pressure on combustion and emission characteristics was evaluated on a common rail direct injection diesel engine fueled with palm oil biodiesel. Recently, many studies have been conducted to utilize biodiesel produced from various sources to prevent environmental pollution and the depletion of petroleum resources. The oxygen content and high cetane number of biodiesel can reduce the production of exhaust pollutants by improving the combustion, but its high viscosity deteriorates the atomization of the injected fuel. Particularly at low engine speed conditions like idle, poor atomization and low airflow in the cylinder deteriorates the combustion efficiency. Increasing the fuel injection pressure is one of the effective methods to improve the atomization of biodiesel without mechanical modification of the current diesel engine. In this study, combustion characteristics and emission levels of pollutants were measured by varying the fuel injection pressure applying palm oil biodiesel. As a result, it was confirmed that increasing the injection pressure to apply palm oil biodiesel at low engine speed can reduce ignition delay and improve combustion efficiency so that nitrogen oxides (NOx) is increased but soot formation is reduced. Carbon monoxide (CO) and hydrocarbon (HC) are slightly reduced but these are increased again when using 100% palm oil biodiesel. The increased NOx due to increased injection pressure can be reduced by applying exhaust gas recirculation (EGR).

Highlights

Environmental pollution and depletion of petroleum resources are accelerating as the use of internal combustion engines using fossil fuels increases [1]
The regulations on exhaust pollutants emitted from internal combustion engines have been strengthened [2,3], and many engineers are exploring methods to improve the efficiency of internal combustion engines
The improvement of engine hardware and precise combustion control reduce exhaust emission while maintaining high performance [4]. Another way to improve efficiency is the improvement of the fuel itself, which is the energy source of the internal combustion engine—that is the use of biofuels

Summary

Introduction

Environmental pollution and depletion of petroleum resources are accelerating as the use of internal combustion engines using fossil fuels increases [1]. The improvement of engine hardware and precise combustion control reduce exhaust emission while maintaining high performance [4]. Another way to improve efficiency is the improvement of the fuel itself, which is the energy source of the internal combustion engine—that is the use of biofuels. Bioethanol and biodiesel are the representative biofuels, and they are considered as alternatives to slow down the depletion of petroleum resources while reducing environmental pollution [5]. Due to its high viscosity, density, and low volatility, bio-oils from raw materials cannot be used in raw form, but through the transesterification process, biodiesel can be produced for use in commercial engines [6]

Methods

Results

Discussion

Conclusion