Emissions From IC Engines Fueled With Alcohol–Gasoline Blends: A Literature Review

Abstract

Since air pollution by automotive exhaust gases is of increasing concern around the world, an examination of the work that has been done with regard to evaluating and reducing it can help focus future efforts in dealing with it. Alcohol-containing fuels not only have been shown to have the potential to produce less of many of the polluting gases, but they also constitute a viable alternative to gasoline from the standpoint of efficiency and reducing dependence on the rapidly dwindling supply of petroleum fuel. This report provides a survey of the literature concerning research reported since 1975 on emissions from IC engines operating on alcohol-gasoline fuel blends. The effects of alcohol on the exhaust emissions (carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and the aldehydes (CHO)) are reviewed. A comparison is made of the emissions benefits achieved when methanol or ethanol is used either in neat form or as the blending agent with gasoline. The primary dependent variable considered is emission level (reported on various bases) with the main independent variables being fuel composition, equivalence ratio, and ignition timing. Brief mention is also made of the potential emissions reduction that may be achieved by using dissociated methanol.

Influence of Air-Fuel Mixtures and Gasoline - Cadoba farinosa forskk Bioethanol Fuel Mixtures on Emissions of a Spark - Ignition Engine.

“…It could be seen from Fig. 6 that all blends have lower values than gasoline owing to higher combustion chamber temperature, which helps in cracking and faster burning [21]. It was observed that the HC emission decreased with increase in engine load (i.e.…”

“…However, at higher loads the effects of viscosity have increased these emission levels for the blends due to poor fuel atomization. As the octane number of ester-based fuel is increased higher than gasoline, it tends to exhibits a shorter delay period and results in better combustion, leading to low HC emission [21].. Previous study have established that, laminar flame speed of alcohol is higher than gasoline [24], and this may assist complete combustion of alcohol-gasoline blend, and result in lower HC emission.…”

“…CO emission increases, as air-fuel ratio becomes higher than the stoichiometric value. The reduction of CO emission at an engine load of 2500g is apparently caused by wide flammability -an inevitable outcome of accelerated flame speed in alcohol in the gasoline blends at high engine speeds [20]; and the' lean effect' generated by the oxygenated characteristic of ethanol, which consequently reduces CO emission [21,22] . …”

Effect of ethanol addition on the performance and exhaust emissions of a spark ignition engine

“…Furthermore, ethanol also acts as fuel additive to improve the engine performance [12]. Some researchers proved that ethanol has several advantages over gasoline such as the reduction of CO and HC emissions burning and better antiknock characteristics, which allow the use of a higher compression ratio of the engine [13][14][15]. Research by Al-Farayedhi [16] on the SI engine showed that the addition of ethanol in gasoline can reduce emissions of CO gas, especially in the rich combustion conditions for the extra oxygen already contained in ethanol (available oxygen contained).…”

Performance Evaluation of Spark Ignited Engine Fueled with Gasoline-Ethanol-Methanol Blends

“…Several studies have been exploited to investigate the influence of methanol and ethanol on the performance of gasoline fueled spark ignition engines [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Ashraf [9] investigated the performance and exhaust emissions from spark-ignition engine fueled with ethanol-methanol-gasoline blends.…”