• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.5
• /
• pp.12-18
• /
• 2004

Transient natures of diesel sprays are often characterized with spray visualization, since it is a non-intrusive and straightforward technique to be applied. However, as injection pressure is increased higher than a thousand bar in a modern direct injection diesel engine, very fine temporal and spatial resolutions in the spray visualization are required while sprays become optically denser. Discussed in this paper are macroscopic and microscopic spray visualization techniques and an example of image processing process for efficient and consistent measurement of spray parameters. The injection rate measurement method based on hydraulic pulse principle was suggested as a way of estimating injection velocity for transient diesel sprays. The spray visualization and injection rate measurement techniques were applied to analyze transient diesel sprays from a common-rail injection system and found to be practically effective.

• Journal of Advanced Marine Engineering and Technology
• /
• v.25 no.6
• /
• pp.1244-1249
• /
• 2001

The characteristics of engine performance with fuel injection system in D.I. diesel engine were studied in this paper A fuel injection system has an important role in the performance and emission gas in a diesel engine. In this paper, an experimental study has been performed to verify the effect of the performance and the emission gas with the factors such as diameters of an injection nozz1e hole, diameters of an injection pipe and injection timing in the fuel injection system. The authors have obtained the results that optimizing the factors of fuel injection system is siginificant to enhance the performance of the engine system and consumption ratio of fuel, smoke, and NOx.

• Journal of ILASS-Korea
• /
• v.6 no.3
• /
• pp.32-37
• /
• 2001

The characteristics of engine performance with fuel injection system in D.I. diesel engine were studied in this paper. A fuel injection system has an important role in the performance and emission gas in a diesel engine. In this paper, an experimental study has been performed to verify the effect of the performance and the emission gas with the factors such as diameters of an injection nozzle hole, diameters of an injection pipe and injection timing in the fuel injection system. The authors have obtained the results that optimizing the factors of fuel injection system is significant to enhance the performance of the engine system and consumption ratio of fuel, smoke, and NOx.

• Journal of Power System Engineering
• /
• v.16 no.3
• /
• pp.16-21
• /
• 2012

Biodiesel is technically competitive with or offers technical advantages over conventional petroleum diesel fuel. Biodiesel is an environmentally friendly alternative liquid fuel that can be used in any diesel engine without modification. In this study, to investigate the effect of fuel injection timing on the characteristics of performance with DBF in DI diesel engine. The engine was operated at five different fuel injection timings from BTDC $6^{\circ}$ to $14^{\circ}$ at $2^{\circ}$ intervals and four loads at engine speed of 1800rpm. As a result of experiments in a test engine, maximum cylinder pressure is increased with leading fuel injection timing. Specific fuel oil consumption is indicated the least value at BTDC $14^{\circ}$ of fuel injection timing.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.10
• /
• pp.1435-1441
• /
• 2003

Combustion characteristics on diesel-water emulsion are analyzed in high pressure injection for several variables such as water content, injection pressure and injection timing. As a fact of well-known, maximum combustion pressure was decreased and ignition delay was elongated in accordance with increasing of water content. But these characteristics were enhanced with increase of injection pressure to high pressure. It was shown that combustion of neat diesel in case of injecting with 600bar is similar to that of 20 % diesel-water emulsion was injected at 1200 bar.

• Journal of the korean Society of Automotive Engineers
• /
• v.12 no.5
• /
• pp.76-84
• /
• 1990

To study diesel fuel spray behavior, an experimental study was undertaken to investigate injection characteristics in vary ing back pressure and atomization mechanism in a non-evaporating diesel spray. Generally, injection characteristics is the curve of fuel flow plotted against time. The area under this curve is equal to the total quantity of fuel discharged for one injection. The method that measures rate of injection is long tube-type fuel rate indicator. Diesel spray injected into a quiescent gaseous environment under high pressure is observed by taking high speed camera by the focused shadow photographs. The results show that, at the start of injection, as the injected fuel rushes into the quiescent atmosphere the spray angle becomes large. Finally the spray stabilizes at a constant cone angle. Spray penetration length increases with the injection pressure.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.3
• /
• pp.201-206
• /
• 2009

The focus of this work is placed on the analysis of the mixture formation process under the evaporative diesel-free spray conditions. In order to examine homogeneity of mixture within the vapor phase region of the injected spray, image analysis was carried out based on the entropy of statistical thermodynamics. As an experimental parameter, the injection pressure and ambient gas density were selected, and effects of the injection pressure and density variation of ambient gas on the mixture formation process in the evaporative diesel spray were investigated. In the case of application of the thermodynamic entropy analysis to evaporative diesel spray, the value of the dimensionless entropy always increases with increase in time from injection start. Consequently, the dimensionless entropy in the case of the higher injection pressure is higher than that of lower injection pressure during initial injection period.

• Journal of Power System Engineering
• /
• v.9 no.4
• /
• pp.214-219
• /
• 2005

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 72MPa to 112MPa by using a common rail injection system(ECD-U2). The images of liquid and vapor phase in the evaporating free diesel spray are simultaneously taken by exciplex fluorescence method. As a result, it can be confirmed that the distribution of vapor concentration is more uniform in the case of the high injection than in that of the low injection pressure.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.4
• /
• pp.1-9
• /
• 2014

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of petroleum fuels. Fast pyrolysis of biomass is one of several paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO) has been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of WPO in a diesel engine requires modifications due to low energy density, high water contents, high acidity, high viscosity, and low cetane number of the WPO. One possible method by which the shortcomings may be circumvented is to co-fire WPO with other petroleum fuels. WPO has poor miscibility with light petroleum fuel oils; the most suitable candidates fuels for direct fuel mixing are methanol or ethanol. Early mixing with methanol or ethanol has the added benefit of significantly improving the storage and handling properties of the WPO. For separate injection co-firing, a WPO-ethanol blended fuel can be fired through diesel pilot injection in a dual-injection dieel engine. In this study, the performance and emission characteristics of a dual-injection diesel engine fuelled with diesel (pilot injection) and WPO-ethanol blend (main injection) were experimentally investigated. Results showed that although stable engine operation was possible with separate injection co-firing, the fuel conversion efficiency was slightly decreased due to high water contents of WPO compare to diesel combustion.

• Journal of Power System Engineering
• /
• v.15 no.5
• /
• pp.10-15
• /
• 2011

This paper describes the engine performance and combustion characteristics of a CRDI diesel engine, operated by electronically controlled diesel fuel injector with variable injection timing. This experiment focused on fuel injection timing and pressure about combustion characteristics of CRDI diesel engine. EGR was excepted because it would be furtherly analyzed with additional experiments. The experiment was conducted under the circumstance of engine torque for 4, 8, 12 and 16 kgf-m and fuel injection timing for $15^{\circ}$, $10^{\circ}$ and $5^{\circ}$ BTDC, at the engine speed of 1100, 1400, 1700 and 2000 rpm. Fuel injection was controlled to retard or advance initiation of the injection event by electronically controlled fuel injection unit injector on the personal computer. When fuel was injected into the cylinders of a CRDI diesel engine it would go through ignition delay before starting of combustion. Therefore, fuel injection timing of CRDI diesel engine had a significant effect upon performance and combustion characteristics. Depending on the injection timing the fuel consumption rate following the rotational speed and torque was 3~78 g/psh (1.7~30.6%). The range of fuel injection timing that resulted in low fuel consumption overall was BTDC 15-10 degrees.