• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.869-874
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• 2011

In a CNG/diesel dual-fuel engine, CNG is used as the main fuel and a small amount of diesel is injected into the cylinder to provide ignition priming. In this study, a remodeling of the existing diesel engine into a CNG/diesel dual-fuel engine is proposed. In this engine, diesel is injected at a high pressure by common rail direct injection (CRDI) and CNG is injected at the intake port for premixing. The CNG/diesel dual-fuel engine had an equally satisfactory coordinate torque and power as the conventional diesel engine. Moreover, the CNG alternation rate is over 89% throughout the operating range of the CNG/diesel dual-fuel engine. PM emission by the dual-fuel engine is 94% lower than that by the diesel engine; however, NOx emission by the dual-fuel engine is higher than that by the diesel engine.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.97-103
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• 2011

The electronically controlled diesel engine was converted to dual fuel engine system. Test engine was set up for investigating the power output, thermal efficiency and emissions. ND 13-mode tests were employed for the engine test cycle. The emission result of dual fuel mode meets Euro-4 (K2006) regulation and the engine performance of dual fuel engine was comparable to the performance of diesel engine. To estimate economical efficiency, test vehicles have been operated on a certain driving route repeatedly. Fuel economy, maximum driving distance per refueling and driveability were examined on the road including free ways. Developed vehicle can be operated over 500 km with dual fuel mode and shows 80% of diesel substitution ratio. Driveability of dual fuel mode is similar with that of diesel mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.210-219
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• 2014

The MPI dual injection engine can enhance the fuel efficiency and engine power. By using one injector per one intake port, MPI dual injection engine has an excellent fuel atomization and targeting injection. As the basic research for the MPI Dual injection engine design, this research was investigated in order to understand the characteristic of the in-cylinder flow and fuel behavior according to engine temperature condition and the fuel type in the MPI dual injection engines. The 3D unsteady CFD simulation for the MPI Dual injection engine was performed using STAR-CD. The engine operating condition was 2,000 rpm/WOT. The parameters for this study were fuel types, fuel temperatures and wall temperatures. As a result, the intake air amount, evaporated fuel in the cylinder and the fuel film on the wall were presented according to parameters that depend on the fuel properties and engine wall temperature. Also, the results were influenced by in-cylinder flow such as the intake flow, back flow and so on.

• Journal of the Korean Institute of Gas
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• v.17 no.6
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• pp.20-26
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• 2013

In this study, based on a 12L class diesel engine, a natural gas-diesel dual fuel engine was developed by adding natural gas fuel supply system. For optimal control of dual fuel engine, a conventional diesel engine ECU and a dual fuel ECU were utilized. To convert the dual fuel engine, MPI natural gas injectors were installed on the new modified intake manifold adapter. As a results, the dual fuel engine showed same level of torque, power performance and exhaust gas emissions as those of a diesel base engine.. Furthermore, overall fuel replacement rate was 70~76 % and total fuel cost saving was 37~40%.

• 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.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.94-99
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• 2012

The characteristics of spray behavior and injected amount were studied with two types of nozzles for using in a compression ignition engine with dual fuel technology for construction machines. A penetration length of spray tends to shorten due to a decrease of injected amount of a diesel fuel with dual fuel engine application. In order to ignite the gaseous fuel premixed with air during intake process, a diesel fuel, which was compression ignited, needs to penetrate somehow similar depth compared with the case of a diesel fuel-only-injection. In this work, a nozzle with reduced hole diameter and increased number of holes was tested and demonstrated that, compared to diesel 100% case, its penetration lengths are comparable to 74% and 79%, respectively, of those of 100% and 50% supply of a diesel fuel with the baseline nozzle that has four holes and 30.4% increased diameter. This will presumably enhancement the combustion in a dual fuel engine. A design suggestion was also made in this work to achieve similar penetration length of spray with diesel 100% case to prevent combustion from being deteriorated in a dual fuel engine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1260-1268
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• 2012

Recently, lack of power reserve margin was observed quite often. In this paper, we studied the method to secure power source for a short time, to cut the utility power peak load, and to reduce the users electricity bills. Emergency diesel generator of an office building is to be converted into a dual-fuel engine generator which is responsible for a portion of the peak load. Compared to the conventional diesel fuel generator, the proposed dual-fuel engine is able to reduce the generation power cost by dual-fuel combustion, and it also mitigates the building's utility power peak load by charging the building's peak load. If the dead resources (a group of emergency dual-fuel engine generators), as a Virtual Power Plant, are operating in peak time, we can significantly reduce future large power development costs. We investigated the current general purpose electricity bills as well as the records of the building electric power usage, and calculated diesel engine generator renovation costs, generation fuel costs, driving conditions, and savings in electricity bills. The proposed dual-fuel engine generation method reduces 18.1% of utility power peak load, and turned out to be highly attractive investment alternative which shows more than 27% of IRR, 76 million won of NPV, and 20~53 months of payback periods. The results of this study are expected to be useful to developing the policy & strategy of the energy department.

• 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.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.99-100
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• 2006

최근 LNG 연료 시장의 호황에 힘입어 LNG선들이 점차 대형화 추세에 있고, LNG선의 추진 기판 또한 경제성, 환경 영향 등의 주어진 요구 환경에 따라 다양화 되고 있다. 기존의 Steam Turbine Propulsion 외에 Conventional 2-stroke Diesel Engine 및 Dual-fuel 4-stroke Diesel Engine 이 LNG선의 주 기관으로 각광받고 있다. 이에 따라 Dual fuel electric propulsion LNGC의 기본 개념, 작동 원리 주요 보조 기기, 타 추진 시스템과의 비교 능에 대해 고찰하였다.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.3
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• pp.215-220
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• 1997

CNG dual fuel engine for heavy duty diesel engine developed by AFS International in Canada has been equipped to a Korean city bus engine and tested to compare the engine performance and the emission characteristics with the existing diesel fueled engine. Also the dual-fuel engine was applied to the city bus for road test. The results are summarized as follows. Performance optimization has been carried out to have engine power equivalent to or better than the diesel fueled engine. Smoke is decreased by 85% by Korean smoke 3 mode test. By 13 mode test CO is increased by 453% and THC is increased by 2, 086%. NOx is decreased by 7% in laboratory. D-13 test mode was changed in 1996 Korean regulation. Even though THC is increased very much, it's not too serious problem since CO and HC emission of diesel engine is very little compared to gasoline engine and more than 75% of THC is CH$_4$. But the reduction technologies of CO and HC has to be considered.