Effect of alcohol blend and fumigation on regulated and unregulated emissions of IC engines-A review

In recent years, the effect of alcohols as an alternative fuel on emissions of IC engines has been investigated in a lot of experimental works. However there is a lack of a comprehensive review study about the definition and type of emissions (regulated and unregulated emissions) and alcohols and the influence of alcohols on unregulated emissions of IC engines. Therefore, this literature review study is presented. In the current literature review work, two sections are provided. A brief detail of the effect of alcohols (methanol and ethanol) in blended and fumigation modes on regulated emissions in IC engines is presented in the first section. And the second section (main section of this work) is a comprehensive review part of the literatures related to the effect of methanol and ethanol in blended and fumigation modes on unregulated emissions in IC engines. In this literature review work, a wide type of IC engines, such as SI and CI engines and motorcycles were collected with different operation conditions. Different percentages of alcohol blend and fumigation were summarized to get informations about the effect of alcohol on regulated and unregulated emissions of IC engines. For regulated emissions, it was found that application of alcohols as alternative fuels in fumigation mode in IC engines led to reduction of NOx and CO2 in most tests and PM in all cases. However, an increase of CO and HC was observed with using alcohols in fumigation mode in most cases. It is noticeable that a diverse effect of alcohol application in blended mode compared to fumigation mode on regulated emissions was recorded in considerable tests except PM. For unregulated emissions, it was found a reduction of BTEX (benzene, toluene, ethylbenzene and o-xylene, map-xylenes) in blended mode in most cases, polycyclic aromatic hydrocarbons (PAHs) in blended mode in major experiments and 1,3 -butadiene, ethyne and ethene in both modes in all tests with using alcohols compared to fossil fuels. On the other hand, it was seen an increase of unburned ethanol and methanol and total carbonyls in both modes in all tests. And, an increase of formaldehyde and acetaldehyde which are the predominant carbonyls in the exhaust for vehicles was recorded in most and major experiments, respectively for both modes. In addition, soluble organic fraction (SOF) had an increase in both modes in major tests. And an increase of benzene, toluene, xylene (BTX) was observed in fumigation mode in significant tests. (C) 2015 Elsevier Ltd. All rights reserved.