The effects of ethanol–unleaded gasoline blends and ignition timing on engine performance and exhaust emissions

doi:10.1016/j.renene.2006.01.004

Renewable Energy

Volume 31, Issue 15, December 2006, Pages 2534-2542

https://doi.org/10.1016/j.renene.2006.01.004 Get rights and content

Abstract

In this study, the effects of using unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E10, E20 E40 and E60) on engine performance and exhaust emissions have been experimentally investigated. The investigation was conducted on a Hydra single-cylinder, four-stroke, spark ignition engine. The experiments were performed by varying the compression ratio (8:1, 9:1 and 10:1) and ignition timing at a constant speed of 2000 rpm at wide open throttle (WOT). The experimental results showed that blending unleaded gasoline with ethanol slightly increased the brake torque and decreased carbon monoxide (CO) and hydrocarbon (HC) emissions. It was also found that blending with ethanol allows increasing the compression ratio without knock occurrence.

Introduction

The rapid depletion of the world's crude oil reserves and environmental considerations has focused on the clean, renewable and sustainable energy systems. The energy crisis and environmental pollution created an incentive to study and evaluate alcohols as a fuel in spark ignition engines [1], [2].

Alcohol fuels and particularly ethanol can be produced from renewable sources, such as sugar cane, cassava, many types of waste biomass materials, corn and barley. Ethanol has some advantages over gasoline, such as the reduction of CO, volatile organic compounds (VOC) and unburned hydrocarbon (UHC) emissions and better anti-knock characteristics, which allow for the use of higher compression ratio of engines. Since ethanol is a liquid fuel, the storage and dispensing of ethanol is similar to that of gasoline [1], [3], [4], [5].

At the present time ethanol is used in spark ignition engines by blending with gasoline at low concentrations without any modification. Pure ethanol can be used in spark ignition engines but necessitates some modifications to the engine [2], [6], [7].

Alasfour [8] conducted performance tests using 30% iso-butanol–gasoline blend as fuel in a single-cylinder, spark-ignition engine. The ignition timing was varied; NO_x emission and knocking phenomena were studied at different fuel–air equivalence ratio. Advancing the ignition timing caused the level of NO_x emission to increase. Retarding the ignition timing caused engine thermal efficiency to decrease.

Al-Baghdadi [9] studied the effect of the amount of hydrogen/ethanol addition on the performance and exhaust emission of a spark ignition engine. The addition of 8% of hydrogen with 30% of ethanol caused a 48.5% reduction in CO emission, 31.1% reduction in NO_x emission and 58.5% reduction in specific fuel consumption. In addition, the engine thermal efficiency and output power increased by 10.1% and 4.72%, respectively.

In an experimental study, carried out by Al-Hasan [6], the effects of using unleaded gasoline–ethanol blends on spark ignition engine performance and exhaust emission were investigated. He found that using unleaded gasoline–ethanol blends leads to an increase in brake power, brake thermal efficiency, volumetric efficiency and fuel consumption by about 8.3%, 9%, 7% and 5.7%, respectively. In addition, CO and HC emission reduced by about 46.5% and 24.3%, respectively. The 20% ethanol fuel blend gave the best results of the engine performance and exhaust emissions.

He et al. [10] investigated the effect of ethanol–gasoline blends on emissions and catalyst conversion efficiencies in a spark ignition engine. The blended fuels reduced CO, HC and NO_x emissions. On the other hand, with the increase of ethanol content in the blend, tailpipe unburned ethanol and acetaldehyde emissions increased.

Abdel-Rahman et al. [11] conducted performance tests using different percentages of ethanol in gasoline fuel, up to 40%, in a variable compression ratio engine. The increase of ethanol content increased the octane number, but decreased the heating value. The engine indicated improved power with the addition of the ethanol in the blend fuel. The optimum blend rate was found to be 10% ethanol and 90% gasoline.

The objective of the present study is to investigate the effect of using unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E10, E20, E40 and E60) on engine performance and exhaust emissions. The tests were performed at a constant speed of 2000 rpm and WOT.

Section snippets

Experimental apparatus and procedure

The experimental study was conducted on a Hydra, single-cylinder, spark-ignition, fuel-injection engine. The general specifications of the engine are shown in Table 1.

The effects of using unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E10, E20 E40 and E60) on engine performance and exhaust emissions have been investigated experimentally. The experiments were performed under variable compression ratio conditions (8:1, 9:1 and 10:1) by varying the ignition timing at a constant speed

Results and discussion

The ignition timing has a significant effect on the performance of spark ignition engines. The variation of brake torque and brake-specific fuel consumption (BSFC) with ignition timing at the compression ratio of 8:1 and 9:1 are shown in Fig. 2, Fig. 3, respectively. Maximum brake torque (MBT) was obtained at 28° CA (crank angle) ignition timing advance with E0 fuel; however, it was obtained at 24° CA ignition timing advance with E60 fuel at the compression ration of 8:1. As seen in Fig. 2,

Conclusions

In this study, the effects of using unleaded gasoline and unleaded gasoline–ethanol blends on engine performance and exhaust emissions were investigated by varying the ignition timing and compression ratio. Based on the experimental study, the following results were obtained:

1.
MBT ignition timing of the engine obtained with blends showed no significant change relative to unleaded gasoline under all compression ratio conditions.
2.
Blending unleaded gasoline with ethanol increased the brake torque

Acknowledgments

This study was supported by the Gazi University Scientific Research Foundation in frame of the project code of TEF.07./2002-27. Fuel tests were performed by the Petroleum Research Center of Middle East Technical University. As researchers we thank the Scientific Research Foundation of Gazi University and Petroleum Research Center of METU.

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Engine performance and pollutant emission of an SI engine using ethanol–gasoline blended fuels
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The use of ethanol–gasoline blend as a fuel in an SI engine
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M. Al-Hasan
Effect of ethanol–unleaded gasoline blends on engine performance and exhaust emission
Energy Convers Manage
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F.N. Alasfour
NO_x emission from a spark ignition engine using 30% iso-butanol–gasoline blend: Part 2—ignition timing
Appl Thermal Eng
(1998)
B.Q. He et al.
A study on emission characteristics of an EFI engine with ethanol blended gasoline fuels
Atmos Environ
(2003)

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Technical NoteThe effects of ethanol–unleaded gasoline blends and ignition timing on engine performance and exhaust emissions

Abstract

Introduction

Section snippets

Experimental apparatus and procedure

Results and discussion

Conclusions

Acknowledgments

Atmos Environ

Renew Energy

Energy Convers Manage

Appl Thermal Eng

Atmos Environ

Technical Note
The effects of ethanol–unleaded gasoline blends and ignition timing on engine performance and exhaust emissions