In this paper, ethylene glycol n-propyl ether palm oil monoester (EGPEPOM) was synthesized through transesterification of refined palm oil and ethylene glycol n-propyl ether with sodium as the catalyst. Its chemical structure was characterized through Fourier transform infrared (FTIR) spectrometry, hydrogen atom nuclear magnetic resonance (1H NMR), and gel permeation chromatography (GPC) analyses. To investigate the engine performance of EGPEPOM, tests on a two-cylinder direct-injection (DI) diesel engine were conducted. Experimental results indicated that the chemical structure of EGPEPOM is consistent with theoretical analysis. In comparison to diesel fuel, the start of combustion was advanced and the peak cylinder pressure was decreased with the EGMEPOM fuel. Meanwhile, the brake thermal efficiency of EGPEPOM was improved. The smoke emission was decreased maximally by 37.5% with brake-specific CO (BSCO) emission reduced by 66.6%, brake-specific hydrocarbon (BSHC) emission reduced by 27.1%, and brake-specific NO
x
(BSNO
x
) emission reduced by 23.7%.
To investigate the effects of fuel temperature on the injection process in the fuel-injection pipe and the combustion characteristics of compression ignition (CI) engine, tests on a four stroke, direct injection dimethyl ether (DME) engine were conducted. Experimental results show that as the fuel temperature increases from 20 to 40 °C, the sound speed is decreased by 12.2%, the peak line pressure at pump and nozzle sides are decreased by 7.2% and 5.6%, respectively. Meanwhile, the injection timing is retarded by 2.2 °CA and the injection duration is extended by 0.8 °CA. Accordingly, the ignition delay and the combustion duration are extended by 0.7 °CA and 4.0 °CA, respectively. The cylinder peak pressure is decreased by 5.4%. As a result, the effective thermal efficiency is decreased, especially for temperature above 40 °C. Before beginning an experiment, the fuel properties of DME, including the density, the bulk modulus, and the sound speed were calculated by "ThermoData." The calculated result of sound speed is consistent with the experimental results.
Ethanol-diesel blended fuel has the potential to reduce diesel engine exhaust smoke and particulate emission as well as partially solve the energy crisis. However, with the increase of the ethanol fraction of the blends, the engine combustion will be affected significantly because of the change of fuel properties, especially the ignition delay (τ ig ). Generally, a cetane number (CN) improver should be added to improve the engine combustion. In this study, E30 (30 vol % of ethanol in the blend) was prepared. A CN improver was added at 0, 0.3, and 0.6% (in volume), respectively. With a two-cylinder diesel engine, the effects of a CN improver on the engine combustion and emissions were investigated. Experimental results show that, in comparison to the diesel engine, the brake thermal efficiency of the E30 engine is improved, the τ ig is prolonged, while the total combustion duration becomes shorter. With the increase of the CN improver fraction, the brake thermal efficiency, diffusive combustion phase, and total combustion duration all increase, while the τ ig decreases. The addition of ethanol and a CN improver in diesel has no effect on nitric oxides (NO x ); however, the particulate matter (PM) and smoke emissions of the E30 engine decrease significantly, and they will be deteriorated with a high fraction blending of a CN improver.
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