• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.221-229
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• 2015

The PFI dual injection engine using one injector per an intake port was developed for solving the DISI engine cost problem. Excellent fuel atomization and targeting of the PFI dual injection engine made enhancement on the fuel efficiency and engine power. In order to develop a PFI dual injection engine, characteristics of the in-cylinder flow and fuel behavior with respect to fuel injection angle and cone angle of the PFI dual injection engine was investigated. Numerical calculation was conducted to analyze 3D unsteady in-cylinder flow and fuel behavior using STAR-CD. The engine operating condition was 2,000rpm at WOT. As a result, the amount of intake air, evaporated fuel and fuel film according to injection angle and cone angle were presented. The results were influenced by interaction between injected fuel and intake port wall.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.178-187
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• 2021

Dual-cooled annular fuel allows a significant increase in power density while maintaining or improving safety margins. However, the dual-cooled design brings much higher Zircaloy charge in reactor core, which could cause a great threaten of hydrogen explosion during severe accidents. Hence, an innovative fuel combined dual-cooled annular geometry and SiC cladding was proposed for the first time in this study. Capabilities of fuel design and behavior simulation were developed for this new fuel by the upgrade of FROBA-ANNULAR code. Considering characteristics of both SiC cladding and dual-cooled annular geometry, the basic fuel design was proposed and preliminary proved to be feasible. After that, a design optimization study was conducted, and the optimal values of as-fabricated plenum pressure and gas gap sizes were obtained. Finally, the performance simulation of the new fuel was carried out with the full consideration of realistic operation conditions. Results indicate that in addition to possessing advantages of both dual-cooled annular fuel and accident tolerant cladding at the same time, this innovative fuel could overcome the brittle failure issue of SiC induced by pellet-cladding interaction.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.51-57
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• 2011

An experimental study was performed to explore characteristics of combustion and exhaust emissions in the compression ignition engine of RCCI (reactivity controlled compression ignition) using diesel-gasoline dual fuel. A dual-fuel reactivity controlled compression ignition concepts is demonstrated as a promising method to achieve high thermal efficiency and low emissions. For investigating combustion characteristics, engine experiments were performed in a light-duty diesel engine over a range of SOIs (start of injection) and gasoline percents. The experimental results showed that cases of diesel-gasoline dual fuel combustion is capable of operating over a middle range of engine loads with lower levels of NOx and soot, acceptable pressure rise rate, low ISFC (indicated specific fuel consumption), and high indicated thermal efficiency.

• Journal of the Korean Society of Combustion
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• v.16 no.1
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• pp.52-57
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• 2011

The present study describes the characteristics of combustion and exhaust emissions in compression ignition engines using diesel-gasoline dual fuel. For investigating combustion characteristics, diesel fuel was injected directly in a single-cylinder compression ignition engine with a common-rail injection system and gasoline fuel was injected into a premixed chamber installed in an intake port. In order to investigate exhaust emission characteristics, exhaust gas was measured by emission analyzer and smoke meter. The experimental results showed that cases of diesel-gasoline dual fuel combustion exhibited extended ignition delay and reduced peak combustion pressure compared to those of directly injected diesel fuel cases. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of rate of heat release(ROHR).

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.38-43
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• 2011

A CNG/diesel dual-fuel engine uses CNG as the main fuel and injects a small amount of diesel as an ignition priming. This study proposed the modification of the existing diesel engine into a dual-fuel engine that injects diesel with a high pressure by common rail direct injection (CRDI) and by injecting CNG at the intake port for premixing. And experiment was progressed for understanding about effect of CNG mixing ratio. The CNG/diesel dual-fuel engine showed equally satisfactory coordinate torque and power regardless of CNG mixing ratio. The PM emission was low at any CNG mixing ratio because of very small diesel pilot injection. In case of NOx and HC, high CNG mixing ratio showed low NOx and HC emissions at low speed. At medium & high speed, low CNG mixing ratio showed low NOx and HC emissions. Therefore, it would be optimized by controlling CNG mixing ratio.

• Journal of Energy Engineering
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• v.19 no.4
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• pp.246-250
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• 2010

It was measured engine power, specific fuel consumption and exhaust emissions to analyze fuel economy between LNG dual fuel vehicle and base diesel one. The tested LNG dual fuel engine is converted from diesel engine having 12 liter heavy duty class. The power of LNG dual fuel engine is 5% lower than diesel one and the engine efficiency is also lower than diesel case. However the exhaust emission of diesel engine such as PM, NOx, CO and $CO_2$ showed higher than that of LNG duel fuel case except NMHC component. And economical analysis were carried out two cases for an aspect of fuel economy and environmental benefit. As a result, LNG dual fuel vehicle gives some economic benefit to whom both business party and public side respectively though considering the subsidy and price discount for diesel.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.112-122
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• 1995

As an alternative fuel producing less exhaust emissions, natural gas is of interest for use both in SI and CI engines. The potential of natural gas fuelled dual-fuel engine is considered high enough. However, much effort has to be made so that gaseous fuel is used efficiently with simultaneous minimum use of pilot oil. Hence, a simplified three-dimensional model, using a finite volume method in cylindrical coordinates, has been developed to facilitate an understanding of the dual-fuel combustion phenomena and to predict the complex interactions between the pilot distillate and natural gas. The computer model was calibrated by comparing it with the experimental results obtained from diesel engine like combustion bomb tests. In the pre-mixed natural gas combustion, the fuel burning was highly reliant on the injection condition and subsequent burning nature of the pilot distillate.

• International Journal of Advanced Culture Technology
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• v.4 no.1
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• pp.10-18
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• 2016

In the present study, a single cylinder four stroke dual fuel diesel engine was tested to investigate the performance and emission characteristics of various test fuels. The engine was tested in dual fuel mode using diesel and Karanja biodiesel blends as pilot fuel along with Natural gas as primary fuel with a constant gas flow rate under different loading conditions. From the experimentation it was found that smoke opacity and oxides of nitrogen (NOx) are at low level for all the prepared test fuels in dual fuel mode but the emissions of carbon monoxide (CO), carbon dioxide ($CO_2$) and hydrocarbon (HC) were found higher. In comparison to diesel fuel, by increasing the blend percentage different emission parameters are found to be reduced. At different loading conditions all the test fuels show poor performance in dual fuel mode of operation when compared with single mode of operation with diesel and biodiesel. With increase in gas flow rates, except (NOx) and smoke emissions, the other emission parameters like CO, HC and $CO_2$ values increased for all test fuels. Again, all blended fuels showed lower performance compared to diesel. The maximum pilot fuel savings for diesel was found decreasing with the increase in karanja biodiesel. From the present work it may be concluded that Karanja biodiesel with Natural gas in dual mode can be can used as promising alternative for diesel with some required engine modifications and further research must be carried out to minimize the emissions of CO, HC and $CO_2$.

• Tribology and Lubricants
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• v.32 no.3
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• pp.82-87
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• 2016

We performed an experimental research on lubricant oil in dual fuel medium-speed engines. It is important to select the appropriate lubricant oil because it could significantly affect engine lifetime and performance. We generally recommend the selection of the lubricant oil according to the fuel grades as contents in the project guide. However, it is a considerable challenge for shipyards to implement this concept because of the lack of space to install the complicated lubricating oil system for dual fuel engines. Therefore, we determine the adaptability of one-common lubricant oil for HiMSEN dual fuel engine through this experimental research. To check abnormality in gas mode operation and durability of engine components when a lubricating oil with high BN (base number) is used, overhaul inspections and lubricant oil analysis are carried out two times, and four times, respectively, during an operation of approximately 300 h. We investigated the variations in kinematic viscosity, base number, element quantity, pentane insoluble and sulfated ash in lubricant oil analysis. Moreover, we also investigated whether the deposit formation or wear occurred in various bearings, injectors, exhaust valves, intake valves, piston rings and so on through the overhaul inspections. There are no problems in the lubricant analysis and the overhaul inspections. Through the experimental research, we confirm that one-common lubricant oil should be selected according to the higher sulfur content of fuel oil in dual fuel engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.30-36
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• 2003

Variable valve timing(VVT) mechanisms are used widely for improving fuel consumption and reducing emissions. Most of application, however, are limited in the DOHC engine. Dual equal retard/advance strategy is relatively simple one and can be applied to both SOHC and DOHC engines. In this study, effects of dual equal valve timing retard/advance are investigated to observe the feasibility of VVT system on an SOHC SI engine. The result shows that fuel economy and emissions are improved in the dual retard condition due to increased internal EGR. Some amount of increase in volumetric efficiency can be achieved by advancing valve timing at low speed and by retarding at high speed. In this case, however, full load power is not so much improved as the volumetric efficiency increases because of severe knock. In the dual advance condition, there is no merit in the fuel economy and emission.