The stricter worldwide emission legislation and growing demands for lower fuel consumption and anthropogenic CO2 emission require significant efforts to improve combustion efficiency while satisfying the emission quality demands. Ethanol fuel combined with gasoline provides a particularly promising and, at the same time, a challenging approach. Ethanol is widely used as an alternative fuel or an effective additive of gasoline due to the advantage of its high octane number and its self-sustaining concept, which can be supplied regardless of the fossil fuel. As a result, vast study has been carried out to study its effects on engine performance and emission. The first part of this article discusses prospect of fuel ethanol as a gasoline substitute. Then it discusses comparative physicochemical properties of ethanol and gasoline. The slight differences in properties between ethanol and gasoline fuels are enough to create considerable change to combustion system as well as behaviors of SI engines. These effects lead to several complex and interacting mechanisms, which make it difficult to identify the fundamentals of how ethanol affects NOx emission. After that, general NOx forming mechanisms are discussed to create a fundamental basis for further discussion. Finally, the article discusses different fuel composition, engine parameter and engine modification effects on NOx formation as well as mathematical approach for NOx prediction using ethanol.

Effect of ethanol–gasoline blend on NOx emission in SI engine

The effect of different alcohol fuels on the performance, emission and combustion characteristics of a gasoline engine

Energy security and global warming concern are the two main driving forces for the global alcohol development that also have the effort to animate the agro-industry. Generally, alcohol and ether fuels are produced from several sources and can be produced locally. Almost all alcohol fuels have similar combustion and ignition characteristics to existing known mineral fuels. Mainly the ether fuels (MTBE and DME) are used as additives at low blending ratio to enhance the octane number and oxygen content of gasoline. The addition of alcohol and ether fuels to gasoline lead to a complete combustion due to the higher oxygen content, thereby leads to increased combustion efficiency and decreased engine emissions. The objectives of this paper are to systematically review the use of alcohols and ethers including butanol, methanol, ethanol, and fusel oil, MTBE, and DME as fuels in SI engine. Also, the current study has investigated the effects of performance (brake torque, brake power, BSFC, effective efficiency, and EGT), emissions (CO, CO2, NOx and HC) and combustion characteristics of SI engine with alcohol and ether. The increase in engine performance could be attained with an increased compression ratio along with the use of alcohol fuels which have a higher-octane value. Furthermore, alcohol and ether burn very cleanly than regular gasoline and produce lesser carbon monoxide (CO) and nitrogen oxide (NOx). On the other hand, the energy value of alcohol and ether fuels is approximately 30% lower than gasoline; thereby the specific fuel consumption (SFC) will increase simultaneously when using alcohol and ether as a fuel. Finally, this paper also discusses the impacts of alcohol on engine vibration, engine noise, and potential to be used as a gasoline octane enhancer. Alcohol can be used as a pure fuel in spark ignition engine, but it requires some modifications to the engine.

Alcohol and ether as alternative fuels in spark ignition engine: A review

Bioethanol fuel obtained from biomass and bioenergy crops has been proclaimed as one of the feasible alternative to gasoline fuel, as it is considered to be clean, renewable and green. In this review, the bioethanol production techniques from different lignocellulosic biomass, and its potential ethanol yield are studied. Moreover, this paper has reviewed the effects of bioethanol fuel blends on spark ignition engine combustion characteristics (i.e. cylinder pressure, cylinder temperature, flame speed, combustion efficiency, combustion duration, heat release rate, knocking and cold start); engine performance parameters (i.e. torque, brake power, brake specific fuel consumption, brake mean effective pressure, brake thermal efficiency and volumetric efficiency); and emission characteristics (i.e. carbon monoxide, oxides of nitrogen, carbon dioxide, unburned hydrocarbon and other unregulated emissions). Recently, many researchers produced bioethanol from herbaceous, industrial and municipal solid wastes (MSW) instead of agriculture and woody biomass. Most of the engine test results showed a remarkable improvement in engine performance and enhanced combustion characteristics for bioethanol fuel. In addition, the carbon monoxide and unburned hydrocarbon emissions decreased. Conversely, carbon dioxide and oxides of nitrogen emissions were not significantly reduced. Furthermore, there was no significant reduction of unregulated emissions, such as aromatics, acetaldehyde, and carbonyls.

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Review on bioethanol as alternative fuel for spark ignition engines

Alcohol fuels have some significant advantages over other alternative fuels, including the ability to work in existing engines as well as the capability to reduce greenhouse gas emissions. This paper analyses the performance and emissions of compression and spark ignition engine using of alcohol fuels from the first aliphatic alcohol family; methanol, ethanol, propanol and butanol. The literature relevant to methanol, ethanol, propanol and butanol was reviewed and summarized to demonstrate its viability as an alternative fuel. The fuel properties of methanol, ethanol, propanol and butanol present the most important properties that allow such fuels as suitable candidates as an alternative fuel for compression and spark ignition engines. The performance and engine emissions indicators such as brake torque, brake power, BTE, BSFC NOx, PM, CO, CO2, HC and soot have been evaluated regarding tone at diesel and gasoline fuels. The results showed that alcohol fuels give different results to engine performance and emissions. Surprisingly, some research yield favorable results to the alcohol as compared to neat diesel and gasoline fuels. It can be concluded that methanol, ethanol, propanol and butanol are capable of reducing harmful engine exhaust emissions, however,at the expense of lower engine performance characteristics.

Alcohol based automotive fuels from first four alcohol family in compression and spark ignition engine: A review on engine performance and exhaust emissions

Li Bin Chiang

Papers

Cold-start emissions of an SI engine using ethanol-gasoline blended fuel

Gasoline displacement and NOx reduction in an SI engine by aqueous alcohol injection