• 한국농공학회논문집
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• 제59권1호
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• pp.109-116
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• 2017

Biomass gasification produces syngas or producer gas as low calorific fuel gas that can be used as a fuel for combustion or prime movers as well as chemical synthesis. Internal combustion engines are readily available with lower costs and easily used for producing distributed power using biomass syngas. In this study, a dual fuel diesel engine was used to evaluate its performance when biomass syngas is used for fuel. The engine was originally developed for biogas application with a diesel engine with a 2,607 cc displacement. Both diesel fuel and syngas consumptions were observed at the different load conditions. The results indicate that the dual fuel engine showed a reasonably good performance and up to 63 % of diesel fuel saving.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.269-274
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• 2011

A CFD analysis was performed to examine the inner channel blockage of dual-cooled fuel which has being developed for the power uprate of a pressurized water reactor (PWR). The dual-cooled fuel consists of an annular fuel pellet($UO_2$) and dual claddings as well as internal and external cooling channels. The dual-cooled annular fuel is different from a conventional solid 려el by employing an internal cooling channel for each fuel pellet as well as an external cooling channel. One of the key issues is the hypothetical event of inner channel blockage because the inner channel is an isolated flow channel without the coolant mixing between the neighboring flow channels. The inner channel blockage could cause the Departure from Nucleate Boiling (DNB) in the inner channel that eventually causes a fuel failure. This paper presents the CFD simulation of the flow through the side holes of the bottom end plug for the complete entrance blockage of the inner channel. Since the amount of coolant supply to the inner channel depends on largely the pressure loss at the side hole, the pressure loss coefficient of the side hole was estimated by the CFD analysis. The CFD prediction of the loss coefficient showed a reasonable agreement with an experimental data for the complete blockage of both the inner channel entrance and the outer channel. The CFD predictions also showed the decrease of the loss coefficient as the outer channel blockage increases.

• 한국분무공학회지
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• 제23권4호
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• pp.192-204
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• 2018

In this study, a 3D CFD analysis method for the combustion process was established for a low calorific value syngas-diesel dual-fuel engine operating under very lean fuel-air mixture condition. Also, the accuracy of computational analysis was evaluated by comparing the experimental results with the computed ones. To simulate the combustion for the dual-fuel engine, a new dual-fuel chemical kinetics set was used that was constituted by merging two verified chemical kinetic sets: n-heptane (173 species) for diesel and Gri-mech 3.0 (53 species) for syngas. For dual-fuel mode operations, the early stage of combustion was dominated by the fuel burning inside or near the spray plume. After which, the flame propagated into the syngas in the piston bowl and then proceeded toward the syngas in the squish zone. With the baseline injection system and piston shape, a significant amount of unburned syngas was discharged. To solve this problem, effects of the injection parameters and piston shape on combustion characteristics were analyzed by calculation. The change in injection variables toward increasing the spray plume volume or the penetration length were effective to cause fast burning in the vicinity of TDC by widening the spatial distribution of diesel acting as a seed of auto-ignition. As a result, the unburned syngas fraction was reduced. Changing the piston shape with the shallow depth of the piston bowl and 20% squish area ratio had a significant effect on the combustion pattern and lessened the unburned syngas fraction by half.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.9-18
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• 1995

The substitution of conventional fuel oil by alternative fuels is of immense interest due to liquid oil shortage and requirements of emission control standard. Among the alternative fuels, natural gas may be the most rational fuel, because of its widespread resource and clean est burning. Meanwhile, engine simulation is of great importance in engine development. Hence a zero-dimensional combustion model was developed for dual-fuel system. Natural gas was injected directly into the cylinder and small amount of distillate was used to provide the ignition kernel for natural gas burning. The intake air and exhaust gas flow was modeled by filling and emptying method. Although the single zone approach has an inherent limitation, the model showed promise as a predictive tool for engine performance. Its simulation was also made to see how the engine performance was influenced by the fuel injection timings and amount of each fuel.

• Advances in Energy Research
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• 제8권3호
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• pp.175-184
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• 2022

The dual-fuel technology, which uses gaseous fuel as the main fuel and liquid as the pilot fuel, is an appealing technology for reducing the exhaust emissions. The current study proposes emission models based on ANFIS for a dual-fuel using producer gas (PG)-diesel engine. Emissions measurements were taken at different engine load levels and fuel injection timings. The proposed model predictions were examined using statistical methods. With R2 values in the range of 0.9903 to 0.9951, the established ANFIS model was found to be consistently robust in predicting emission characteristics. The mean absolute percentage deviate in range 1.9 to 4.6%, and mean squared error varies in range 0.0018 to 13.9%. The evaluation of the ANFIS model developed shows a reliable claim of intrinsic sensitivity, strength, and outstanding generalization. The presented meta-model can be used to simulate the engine's operation in order to create an efficient control tool.

• 한국가스학회지
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• 제11권4호
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• pp.54-58
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• 2007

본 연구에서는 13L급 전자제어식 디젤 엔진을 혼소 엔진으로 개조하여 얻은 결과를 다루고 있다. 혼소 엔진 개조 후 차량의 출력, 연료경제성, 운전성 등을 파악하기 위하여 일정한 경로의 고속도로를 주행하였다. 개조된 차량은 최대 85%의 대체율을 가지며 500 km의 거리를 혼소 모드로 주행하였다. 차량의 주행성능은 디젤 모드의 경우와 거의 동일하였으나, 추월 가속성능이 약간 떨어지는 경향이 있었다. 엔진의 최대출력, 열효율, 배기가스 측정을 위하여 차량 시험과는 별도로 엔진 시험도 동시에 수행하였다. ND-13모드에서 배출가스 배출량 측정 실험을 수행한 결과, 산화촉매를 장착한 혼소모드에서의 배출가스 배출량은 디젤모드에서와 출력은 동일하게 유지하면서 K2006 규제를 만족함을 알 수 있었다.

• 전기화학회지
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• 제13권3호
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• pp.193-197
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• 2010

In terms of the system efficiency, it is very useful to apply the ejector into the fuel recirculation system of a fuel cell system since the ejector needs no parasitic power to operate. Since the conventional automotive fuel cell use hydrogen and air as their fuel, the only hydrogen is needed to be recirculated for the better fuel efficiency. On the other hand, the submarine fuel cell needs both hydrogen and oxygen recirculation systems because the submarine drives under the sea. In particular, the cathodic recirculation has to meet the tougher target since the oxygen based pressurized stack generally used in the submarine applications generates the significant amount of the water in the stack during the operation. Namely, the oxygen utilization has designed less than 50% in the whole operating range for the better exhausting of the generated waters. And thereby in terms of the oxygen utilization, the entrainment ratio of the ejector should be more than 1 within the whole operating range. However, the conventional ejector using a constant nozzle can not afford to satisfy the mentioned critical requirement. To overcome the problem, the dual-ejector and its control strategy are designed. The performance of the proposed dual-ejector is verified by the experiments based on the real operating conditions of the target submarine system. Furthermore, the proposed design method can be used for the other fuel recirculation system of a large-scale fuel cell system with the critical requirement of the fuel utilization.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.372-379
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• 2020

Ammonia-hydrogen dual-fuel engine is a way to reduce greenhouse gas emission because ammonia and hydrogen are carbon-free fuels. In ammonia-hydrogen dual-fuel engine, hydrogen is supplied to improve the combustion characteristic of ammonia. In this study, an ammonia reformer was developed to supply hydrogen for 10 kW class ammonia-hydrogen dual-fuel engine. Thermodynamic characteristic and catalyst were investigated for ammonia reforming. Heat transfer was important for high ammonia conversion of ammonia reformer. 99% of ammonia conversion was obtained when 10 LPM of ammonia and 610℃ of hot gas were supplied to the ammonia reformer.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.179-188
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• 2003

The spray characteristics of dual orifice injector were investigated under two different fuels through measurement of SMD, number density and volume flux by using PDPA system. In this experiment, we found out that the droplet size and spray structure are strongly depend on fuel density and viscosity.

• 한국대기환경학회지
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• 제7권1호
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• pp.31-40
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• 1991

This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.