Performance of Combustion and Emissions Characteristics of Ethanol Dual Injection Spark Ignition Engine

Nizar F.O Al-Muhsen,Guang Hong,Firas Basim Ismail

doi:10.15282/ijame.18.3.2021.20.0697

Abstract

Ethanol dual injection (DualEI) is a new technology to maximise the benefits of ethanol fuel to the spark-ignition engine. In this study, the combustion and emissions characteristics in a DualEI spark-ignition engine with a variation of the direct injection (DI) ratio and engine speed were experimentally investigated. The volume ratio of DI was varied from 0% (DI0%) to 100% (DI100%), and two engine speeds of 3500 and 4000 RPM were tested. The spark timing for maximum brake torque (MBT) was first determined, and then the results of the effect of DI ratio on the engine performance at the MBT conditions were discussed and analysed. The results showed that the MBT timing for the DI and spark timings were 330 and 30 CAD bTDC, respectively. At the MBT timing, the indicated mean effective pressure slightly increased from 0.47 to 0.50 MPa when the DI ratio increased from DI0% to DI100%. However, the maximum combustion pressure significantly decreased by 8.32%, and volumetric efficiency increased by 4.04%. This was attributed to the reduced combustion temperature due to the cooling effect of ethanol fuel enhanced by the DI strategy. The indicated specific carbon monoxide and hydrocarbons significantly increased due to poor mixture quality caused by fuel impingement associated with the overcooling effect. However, the indicated specific nitric oxides significantly decreased due to the temperature reduction inside the combustion chamber. Results showed the potential of DualEI to increase the compression ratio and consequently increase the engine thermal efficiency without the risk of engine knock.

Highlights

The ever increasingly tightened regulations have been enforced to reduce emissions produced by internal combustion (IC) engines
This paper aims to investigate the effect of the volume direct injection (DI) ratio on combustion and emissions characteristics of a naturally aspirated SI engine equipped with a dual injection (DualEI) system
The maximum brake torque (MBT) window for this DualEI engine was experimentally determined at four sparks and DI timings, which are more likely to produce the maximum output power with the best combustion quality [30]

Summary

Introduction

The ever increasingly tightened regulations have been enforced to reduce emissions produced by internal combustion (IC) engines. Ethanol is a renewable fuel that can offset its carbon dioxide (CO2) impact because it is produced from a range of bio-resources. This possibly leads to a partially virtuous production-consumption cycle. Ethanol has a lower heating value, which increases the mileage fuel consumption compared to gasoline [6, 7]. Flex-fuel systems were widely used as auxiliary system to aid SI engine cold starting by using gasoline port injection (GPI) [10]. The flex-fuel vehicles mostly were equipped with conventional port fuel injection systems resulting in moderate engine performance and relatively poor mileage fuel economy

Objectives

Results

Conclusion