Behaviour of Oxygenated Biofuels in Engines: Engine Features of Oxygenate Mixtures

Behaviour of Oxygenated Biofuels in Engines: Engine Features of Oxygenate Mixtures

A. Prabu
DOI: 10.4018/978-1-7998-2539-5.ch010
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An experimental investigation was conducted to disclose the outcomes of oxygenate mixture as additives in Jatropha biodiesel on the performance, combustion, and emission characteristics of a direct injection compression ignition engine. The experiments were conducted in an instrumented single-cylinder, air-cooled, four-stroke, direct-injection diesel engine, equipped with data acquisition system, AC alternator, and an electric loading device. Four oxygenate additives, namely, Ethylene Glycol (C2H6O2), Di methyl Carbonate (C3H6O3), 2-Butoxyethanol (C6H14O2), & Propylene Glycol (C3H8O2) were selected and nine different combinational oxygenate test fuels were prepared attaining ratios of 1, 2, and 4% volume of oxygenates with biodiesel. A significant reduction of emissions such as CO by 60%, Unburned HC by 11%, and smoke emissions by 27% were observed. Substantial improvement in brake thermal efficiency by 6% was observed, while NO emission increased marginally by 4%.
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  • Four oxygenates namely, Dimethyl Carbonate (C3H6O3), Ethylene Glycol (C2H6O2), Propylene Glycol (C3H8O2) and 2-Butoxyethanol (C6H14O2) were selected as fuel additives.

  • Ratios of 1, 2 and 4% volume of oxygenates were blended with Jatropha biodiesel.

  • The brake thermal efficiency for oxygenates dispersed test fuels was substantially improved compared to that of neat biodiesel operation.

  • The oxygenate-dispersed test fuels reduced CO emission by 60%, Unburned HC emission by 11% and smoke emission by 27%.

  • The addition of oxygenates as additives in biodiesel resulted in enhanced performance and emission characteristics of a diesel engine.



Biodiesels are conceived as substitute fuels for petroleum products. Various efforts are established to examine the potency and suitability of the fuel. Biofuels have received more attention than other renewable fuels, as it has better fuel properties than those of petroleum fuel and suppress the environmental pollution. Lower emissions (aldehydes, polycyclic aromatic hydrocarbons and carbon monoxide), lower toxicity and sulphur dioxide emissions are the advantage of biodiesel fuel, having some of the disadvantages such as higher fuel consumption, lower calorific value, higher nitrous oxide (NOx) emissions, low stability and higher freezing point than diesel fuel. Blending biodiesel with additives significantly eliminates the disadvantages of it (Prabu and Anand, 2018). An additive for the fuel has to be selected carefully based on its functions. The commonly used additives in fuel are listed in Table 1.

Table 1.
The commonly used additives in fuel
S.NoTypes of AdditivesFunction
1Anti-Foam AgentsReduce foaming during tank filling
2AntioxidantsInhibit oxidation, reduce precipitate and gum formation, extend storage life,
3BiocidesInhibit fungi and bacterial growth, prevent fuel filter plugging
4Cetane Number ImproverImproves ignition quality by increasing cetane number, easy start of engine, reduces white smoke
5Cloud Point Depressants (Suppressants)Reduces temperature at which paraffin solubilize
6Demulsifiers / DehazersIncrease the rate of water separation from the fuel
7Detergents / DispersantsImproves spray patterns and clean injectors
8Lubricity ImproversImprove lubricity, better injector and pump lubrication
9Metal DeactivatorsDeactivate copper compounds in fuel and promotes longer storage life
10NanoparticlesEnhanced surface area to volume ratio improves the evaporation characteristics.
11OxygenatesImproves the oxygen content in the fuel
12Pour Point DepressantsImprove cold-flow properties and low temperature operability
13Rust PreventorsReduce formation of rust in fuel systems and storage tanks
14Smoke SuppressantsReduce exhaust smoke and promote more complete combustion,
15StabilizersInhibits oxidation and extends storage life

Key Terms in this Chapter

DMCPG1: Biodiesel + 0.5% Propylene glycol + 0.5% Dimethyl Chloride

EGBE1: Biodiesel + 0.5% Ethylene Glycol + 0.5% 2-Butoxy Ethanol

CO: Carbon Monoxide

DMC: Dimethyl Chloride

HC: Hydrocarbon

NO: Nitric Oxide

DMCBE2: Biodiesel + 1% 2-Butoxy ethanol + 1% Dimethyl Chloride

EGT: Exhaust Gas Temperature

ASTM: American Society for Testing and Materials

Btd: Before Top Dead Centre

DMCBE1: Biodiesel + 0.5% 2-Butoxy ethanol + 0.5% Dimethyl Chloride

EGBE2: Biodiesel + 1% Ethylene Glycol + 1% 2-Butoxy Ethanol

EGBE4: Biodiesel + 2% Ethylene Glycol + 2% 2-Butoxy Ethanol

DMCPG4: Biodiesel + 2% Propylene glycol + 2% Dimethyl Chloride

BSFC: Brake Specific Fuel Consumption

BE2: Butoxy ethanol

FFA: Free Fatty Acid

DMCPG2: Biodiesel + 1% Propylene glycol + 1% Dimethyl Chloride

BTE: Brake Thermal Efficiency

Bmep: Brake Mean Effective Pressure

DMCBE4: Biodiesel + 2% 2-Butoxy ethanol + 2% Dimethyl Chloride

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