Table 1. Previous Studies Based on Different Types of Alcohol Fuels.

author	alcohol fuels	BTE	BSFC	HC	CO	NOX	smoke	ref
Deshmukh et al.	n-butanol (10–40%)	less compared to diesel but increased with further addition of alcohol, possibly due to improved combustion characteristics attained by the presence of excess oxygen	increased BSFC due to lower heating values	HC increased due to higher latent heat of vaporization	less due to leaning effect of alcohols	less due to lean composition and lower energy content		(33)
	n-octanol (10–40%)	similar to diesel at lower and medium loads due to relatively closer heating values	increased BSFC due to lower heating values	HC decreased due to increasing oxygen content	less due to leaning effect of alcohols	less due to lean composition and lower energy content
Ashok et al.	n-octanol with biodiesel (biodiesel + 10–50% oct)	increased due to higher oxygen content		increases in higher concentrations due to overleaning of alcohol	less due to higher oxygen content	increased at higher concentrations as rich O2 content supersedes the cooling effect of octanol	less due to the presence of excess oxygen molecules	(34)
Mourad et al.	ethanol (10–50%)	increased possibly due to increased oxygen content at higher blend ratios	increased due to heating values	increased in blends of high alcohol content due to lesser heating values	increased in blends of high alcohol content due to lesser heating values	increased with increasing alcohol ratio due to excess oxygen content		(35)
Agarwal et al.	methanol (10–20%)	increased due to higher flame speed of methanol blends	decreased due to the presence of oxygen content in their molecules	increased due to lower in-cylinder temperature at lower speeds but may inverse at higher speeds	decreased at lower loads due to superior mixing of fuel and air, also decreased at higher loads due to combustion at higher temperatures	decreases due to lower in-cylinder temperature	decreased due to high oxygen content and less carbon content	(36)
Yaman et al.	pentanol (5–20%)	increased due to appropriate atomization characteristics and acceleration in the mixing process		decreased due to improved combustion reaction, resulting from excess oxygen content	lesser due to fewer carbon atoms present in the blend	decreases with increase of alcohol concentration due to high latent heat of vaporization and low adiabatic flame temperature, which decreases the in-cylinder temperature		(37)
Nour et al.	hexanol (10–50%)	increases due to high oxygen concentration, which increases ignition delay	increased due to lower energy content compared to diesel			decreased due to the reduction of flame temperature due to the high enthalpy of vaporization of n-hexanol	decreases with increase in hexanol proportion as the excess oxygen content accelerates the soot oxidation process	(38)