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Eco friendly biofuels for CI engine applications 421

CO 2 + sunlight Plant biomass

Starch, free Lignocellulose
sugars

C6-sugars C5-sugars Syngas

Cyanobacteria Yeasts Bacteria

Ethanol, butanol, isobutanol and higher alcohol

Fig. 15.8 Production process of ethanol and other higher alcohols [20].

Table 15.3 Properties of some alcohols and diesel [21]

Property/fuel Diesel Ethanol Butanol Pentanol
Molecular formula C X H Y C 2 H 5 OH C 4 H 9 OH C 5 H 11 OH
Lower calorific value 42–44 26.79–26.82 32.90–33.2 34.64–34.93
(MJ/kg)
Kinematic viscosity at 2.43–4.0 1.08–1.50 2.23–2.62 2.90
2
40°C (mm /s)
3
Density at 15°C (kg/m ) 820–844 790 808–811 815.1
Oxygen content (%) – 34.73 21.58 18.16
Cetane number 40–55 8–11 17–25 18.3–20.4
Flash point (°C) 55–88 13–17 30–37 49.4

15.4.1.1 Performance characteristics of alcohols
Engine parameters that delineate the performance characteristics of the engine such as
BTE and BSFC resulting from the use of alcohols in CI engines are discussed in detail
in the following section.