Experimental investigation on performance and emissions of a direct-injection diesel engine fueled with biodiesel-ethanol blends

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Experimental investigation on performance and emissions of a direct-injection diesel engine fueled with biodiesel-ethanol blends

 

Author: Li, Dongfang
Title: Experimental investigation on performance and emissions of a direct-injection diesel engine fueled with biodiesel-ethanol blends
Degree: M.Sc.
Year: 2016
Subject: Biomass energy.
Diesel motor -- Alternative fuels.
Diesel motor -- Combustion.
Diesel motor exhaust gas
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Mechanical Engineering
Pages: iv, 127 pages : color illustrations
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2910936
URI: http://theses.lib.polyu.edu.hk/handle/200/8593
Abstract: To reduce air pollution and reliance on fossil fuel, biofuels have been widely investigated for potential application in diesel engines. The purpose of this study is to clarify the influences of biodiesel-ethanol blends on the performance, combustion properties and emission characteristics of a diesel engine. Experiments were conducted on a direct-injection diesel engine fueled with biodiesel, BE5 (95% biodiesel and 5% ethanol on volume basis, v/v), BE10, BE15 and diesel, relatively under 5 different engine loads from 10% to 80% of the full load and with a constant engine speeds of 1800RPM. Biodiesel could lead to higher nitrogen oxides (NOX) emissions and larger numbers of smaller particles compared with standard diesel fuels. Therefore, investigations based on the biodiesel-ethanol blended fuels were conducted in this study. It is found that the blended fuels result in decreased particular matter (PM), carbon monoxide (CO) and unburned hydrocarbon (HC) emissions, as well as reduction in the NOX emissions and the geometric mean diameter (GMD) of the exhausted particles. Compared the pure biodiesel and ultra-low sulfur diesel (ULSD), biodiesel-ethanol blended fuels could also reduce the total number concentration (TNC) of the exhausted particles. The number-fraction of volatile and non-volatile substance in the particles were investigated through the scanning mobility particulate sizer (SMPS) associated with a thermo-denuder (TD). The number based volatile particles for all the testing fuels first decreased and then increased with the engine load. It could be found that particles produced by biodiesel-ethanol blended fuels exhibited higher volatile fraction than those produced from diesel and biodiesel fuels at all the engine loads. In addition, for particles with diameter in the three size groups (DP < 50 nm, 50 nm < DP < 100 nm, DP >100 nm), the volatile fraction in particles with diameters less than 50 nm exhibited higher at low engine load, while at medium and high engine load the particles with diameters 50-100 nm showed higher values in volatile fraction for each tested fuel. While for the particles with diameter above 100nm, an increasing trend of the proportion of volatile substances with the increasing engine load was observed. Particulate samples were collected at all the five engine loads for analyzing the particulate size, morphology and nanostructure characteristics. Higher engine load could contribute to higher primary particulate diameter and less disordered nanostructure for all the testing fuels. Ethanol fraction in the blended fuels showed a positive effect on reducing the primary particulate size, however, the tortuosity of the nanostructure of the particles exhibited an increasing trend with the increasing ethanol percentage, indicating that particles from biodiesel-ethanol blends should have shorter and more curved graphene layer, compared with those generated from pure biodiesel and standard diesel.

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