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The current work applies L9 (33) Orthogonal Array (OA) of Taguchi design to obtain an optimum combination of nature of fuel, speed of engine, and load for DI- CI diesel engine that is alternatively fueled with waste cooking oil (WCO) based pure biodiesel (B100) & 20% blend of biodiesel with neat diesel (B20) with an objective to achieve maximum reduction in smoke and NOx emissions and to enhance the output parameters like engine's heat release, cylinder pressure and brake power with the conceivable dwindling of brake specific fuel consumption of the engine at various load conditions. The optimal input parameters (nature of fuel as B100, speed as 2300 rpm and load as 100%) were specified by the grey relational analysis in such a way that the preferred output results are successfully accomplished. Furthermore, analysis of variance (ANOVA) technique showed that the nature of fuel is the major leading factor with 44.28% impact on the output parameters. The experimental and ANN simulated results at the predicted optimal combination ensured the significant improvements of output response factors, thus validating the use of Grey-Taguchi method in reducing emissions and improving combustion and performance simultaneously. [ABSTRACT FROM AUTHOR]

For compression ignition (CI) engines, two of the fuel injection parameters affecting the engine's performance and emissions formation, are fuel injection timing (FIT) and injector opening pressure (IOP). Other such parameters include the number of injections, rate of injection and injection pattern, etc. In the present study, a multi-cylinder, turbocharged, four-stroke, direct injection (DI) diesel engine was used to investigate the combined influence of FIT and IOP on performance and emissions characteristics. The experimentation was conducted for two IOPs (250 and 300 bar) with four FITs such as 20°, 23°, 26°, and 29° before top dead center (BTDC) at different engine speed and load conditions. To obtain the emissions characteristics, the engine was tested in accordance with the 8-mode steady-state cycle. Moreover, 250 bar and 23° BTDC were the original IOP and FIT, respectively. For all IOP conditions, in comparison to the results with the original FIT, the advancement or retardation in FIT provided the negative results in terms of brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC). Increasing the IOP from 250 to 300 bar, improved the performance parameters for retarded and original FITs (20° and 23° BTDC) and caused the deterioration in performance for advanced FITs. In terms of emissions characteristics, filter smoke number (FSN) and emissions of carbon monoxide (CO) and unburned hydrocarbon (UHC) decreased on advancing the FIT and increasing the IOP. On the other hand, oxides of nitrogen (NOx) and carbon dioxide (CO2) increased on advancing the FIT and increasing the IOP for all experimental conditions. The maximum improvement in the performance of the engine was observed at increased IOP with the original FIT. The original IOP with retarded FIT resulted in the minimum NOx and CO2 with a significant reduction in performance. Furthermore, improvement in performance and reduction in emissions were observed when the engine was operated at higher IOP and retarded FIT. [ABSTRACT FROM AUTHOR]

An integrated performance analysis of a vanadium-based urea-SCR system used for the reduction of exhaust emissions from a diesel engine was carried out. The engine was run on an AC electrical dynamometer in accordance with an 8-mode steady-state cycle. The number-size distribution of particles and carbonyls was analyzed using an electrical low pressure impactor (ELPI) and high performance liquid chromatography (HPLC), respectively. It was found that conversion and/or reduction efficiency (RE) of the SCR were highly affected by the catalyst temperature and space velocity (SV). The NO~ pollutants were greatly reduced with the decrease in SV within the load modes of cyclic speeds. The SCR exhibited an RE of more than 50% for NO~ emissions at 321-435 °C, while the maximum RE was 80.5%. Total hydrocarbon (HC) emissions were also increased with the decrease in load for both cyclic speeds, while the RE varied from 38.7% to 71.1%. Significant increases in upstream and downstream carbon monoxide (GO) emissions were noticed with the decrease in engine load. Reluctance to reduction or a negative RE, ranging from 1.5% to 72%, was observed for CO emissions with the SCR. In addition, nanoparticles were greatly reduced, whereas particles of the size range 57-255 nm showed less reduction. The number-size distribution of particles was shifted from smaller to larger sizes with the SCR retrofit. Furthermore, a substantial conversion of up to 55.3% was obtained in the case of carbonyl emissions. The maximum RE was 58%, 67%, 50%, and 64% for formaldehyde, acetaldehyde, acrolein and acetone, and propionaldehyde, respectively. [ABSTRACT FROM AUTHOR]

• Novel and non-metallic Graphite nano fuel additives are introduced to replace Fe 2 O 3. • Graphite results in higher Cetane index and fuel conversion efficiency than Fe 2 O 3. • Compared to Fe 2 O 3 , G blends result in higher BTE and lower bsfc at 95% confidence. • Graphite nanodiesel produce 17% lower NO x emissions than Fe 2 O 3 blends. Increased menacing engine emissions and threat to human health from metallic combustion catalysts demand a shift towards the application of non-metallic fuel additives. Therefore, the current study is an effort, conducted to introduce a new, less toxic and non-metallic graphite (G) nano diesel-fuel additive, by investigating its effects on the performance and regulated gaseous emissions of a four-cylinder, water-cooled, compression ignition (CI) engine. The experiments were also repeated with Iron oxide (Fe 2 O 3) nanoparticles and statistical analyses were implemented to have a comparison with graphite nanoparticles. The G and Fe 2 O 3 nanoparticles, in concentrations of 50, 100 and 150 mg per litre (mg/l), were mixed with neat diesel by magnetic stirring to prepare homogeneous fuel blends. The physicochemical properties of the fuel blends were determined. A maximum decrease of 4.9% in viscosity and an increase of 3.26% in Cetane index was observed for graphite blends. The investigated parameters include torque (T), brake power (BP), brake specific fuel consumption (bsfc), brake thermal efficiency (BTE), carbon monoxide (CO) and nitrogen oxides (NO x) emissions at engine speed varying from 1500 to 3000 rpm with an interval of 300 rpm at full load. The results revealed that at a confidence level of 95% (significance level α = 0.05), G-blends indicated a higher increase in torque, power, BTE and a greater decrease in bsfc than Fe 2 O 3 blends. Graphite blends produced significantly lower NO x emissions than Fe 2 O 3 treated blends. The increase in T, BP and BTE was 2.4%, 8.9% and 3.9% respectively, with 150 mg/l Fe 2 O 3 blends and 2.9%, 9.6% and 4.1% respectively, with 150 mg/l G-blends. Graphite blends resulted in a 2.6% reduction in bsfc. The increase in NO x emissions was 34.7% with Fe 2 O 3 and 29.2% with G at concentrations of 150 mg/l. The CO increased by 14.2% with G blends. A negative statistical correlation was observed for CO emissions between G and Fe 2 O 3 blends. We conclude that G nanoparticles are more environmentally friendly fuel additives than Fe 2 O 3; however, their application is more recommended for large turbocharged CI engines with improved oxygen density in inlet compressed air. [ABSTRACT FROM AUTHOR]

Abstract: The characteristics of carbonyl compounds emissions were investigated on a direct injection, turbocharged diesel engine fueled with pure biodiesel derived from soybean oil. The gas-phase carbonyls were collected by 2,4-dinitrophenylhydrazine (DNPH)-coated silica cartridges from diluted exhaust and analyzed by HPLC with UV detector. A commercial standard mixture including 14 carbonyl compounds was used for quantitative analysis. The experimental results indicate that biodiesel-fueled engine almost has triple carbonyls emissions of diesel-fueled engine. The weighted carbonyls emission of 8-mode test cycle of biodiesel is 90.8mg(kWh)−1 and that of diesel is 30.7mg(kWh)−1. The formaldehyde is the most abundant compound of carbonyls for both biodiesel and diesel, taking part for 46.2% and 62.7% respectively. The next most significant compounds are acetaldehyde, acrolein and acetone for both fuels. The engine fueled with biodiesel emits a comparatively high content of propionaldehyde and methacrolein. Biodiesel, as an alternative fuel, has lower specific reactivity (SR) caused by carbonyls compared with diesel. When fueled with biodiesel, carbonyl compounds make more contribution to total hydrocarbon emission. [Copyright &y& Elsevier]