• Title, Summary, Keyword: Fuel efficiency

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Effects of Key Operating Parameters on the Efficiency of Two Types of PEM Fuel Cell Systems (High-Pressure and Low-Pressure Operating) for Automotive Applications

  • Kim Han-Sang;Lee Dong-Hun;Min Kyoungdoug;Kim Minsoo
    • Journal of Mechanical Science and Technology
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    • v.19 no.4
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    • pp.1018-1026
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    • 2005
  • The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were con­sidered. The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using muli­object variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.

MULTI-RUN EFFECTS ON THE SOLID FUEL RAMJET COMBUSTION

  • Tae-Ho Lee
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.3-8
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    • 1995
  • An experimental investigation was conducted in order to figure out the multiple fire effects on the combustion efficiency and fuel properties of the solid fuel ramjet. Pure HTPB and metallized $B_4$C/HTPB fuel were studied. Fuel property effects were analyzed by using differential scanning calorimetry, The thermal or mechanical properties of the fuel grain were not affected and the combustion efficiency was a little increased.

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Performance Characteristics of Direct Methanol Fuel Cell with Methanol Concentration (메탄올 농도에 따른 직접 메탄올 연료전지의 성능 해석)

  • Cho, Chang-Hwan;Kim, Yong-Chan;Chang, Young-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.3
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    • pp.197-204
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    • 2008
  • DMFC(Direct Methanol Fuel Cell) is one of promising candidates for power sources of small mobile IT devices like notebook, cell phone, and so on. Efficient operation of fuel cell system is very important for long-sustained power supply because of limited fuel tank size. It is necessary to investigate operation characteristics of fuel cell stack for optimal control of DMFC system. The generated voltage was modeled according to various operating condition; methanol concentration, stack temperature, and load current. It is inevitable for methanol solution at anode to cross over to cathode through MEA(membrane electrode assembly), which reduces the system efficiency and increases fuel consumption. In this study, optimal operation conditions are proposed by analyzing stack performance model, cross-over phenomenon, and system efficiency.

A Study of Power Output Characteristics for the Magnesium Metal Fuel Cell (마그네슘 금속연료전지의 출력특성에 관한 연구)

  • Kim, Yong-Hyuk
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.3
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    • pp.212-217
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    • 2014
  • The electric power output characteristics of magnesium fuel cell were investigated with regard to internal resistance. A equivalent circuit with the series-connected three internal resistance was introduced to analyze of the response to change of power. The power output analysis was employed in order to investigate the effect of internal resistances for the electrolyte concentration, air electrode area, Mg electrode area and distance between the electrodes. It was confirmed that internal resistance is generated by the electrolyte, air electrode and metal electrode, then those Internal resistances had a significant effect on the power output decrease. The power output was a maximum when the load resistance maches the internal resistance of the magnesium fuel cell. The fuel efficiency was only 50% at maximum power output. Higher fuel efficiency was achieved when the load resistance is greater than the internal resistance.

A Study on the Performance Assessment of Nuclear Fuel Debris Filtration Using the Weighted Mean (가중평균을 이용한 핵연료 이물질 여과성능 평가에 관한 연구)

  • Park, Joon Kyoo;Lee, Seong Ki;Kim, Jae Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.2
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    • pp.149-156
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    • 2017
  • Nuclear fuel requires high reliability and safety and therefore contains debris filtering devices to prevent failure-inducing debris from entering it. The debris filtering performance of nuclear fuel is one of the most important factors for fuel integrity. Therefore, the performance must be evaluated and the measurement must be reasonable. In this study, a calculation method of the comprehensive filtering efficiency using the weighted mean was proposed to establish a standard filtering efficiency index. To confirm the suitability of the proposed method, representative debris specimens were selected and the filtering efficiency with the weighted mean was compared with the efficiency of the arithmetic mean. The weighting factor of the weighted mean was introduced to produce a fair evaluation. In addition, the analysis of the debris filtering mechanism was performed according to the size of debris specimens, and the main dimensions of the filtering feature for commercial nuclear fuel.

Effect of Ultrasonic Energy in the Engine using Diesel Fuel Blended Rape-seed Oil (유채혼합유를 사용하는 기관에서 초음파에너지의 영향)

  • Kwon, K.R.;Ko, K.N.
    • Journal of the Korea Society For Power System Engineering
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    • v.9 no.4
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    • pp.5-10
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    • 2005
  • The effect of ultrasonic energy for diesel fuel and blend oil has been revealed in this paper. The experimental setup consisted of a high speed diesel engine with 4 cylinder, dynamometer and ultrasonic fuel feeding system. Ultrasonic energy was added to diesel fuel and blend oil, which is a blend of diesel fuel and rape-seed oil. As engine speed was changed, engine torque and power, brake specific fuel consumption and thermal efficiency were measured in detail. As the results, by adding ultrasonic energy to diesel fuel and blend oil, the engine performance was improved in range of the experiment. The effect of improvement on brake specific fuel consumption and thermal efficiency for blend oil is higher than that for diesel fuel. When ultrasonic energy was added to diesel fuel or blend oil, a rise in engine torque for diesel fuel was higher than that for blend oil, but the effect of ultrasonic energy was small. From these results, it may be desirable to add ultrasonic energy to blend oil for the use of blend oil to diesel engine.

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Optimal Design of RSOFC System Coupled with Waste Steam Using Ejector for Fuel Recirculation (연료 재순환 이젝터를 이용한 연료전지-폐기물 기반 가역 고체 산화물 연료전지의 최적 설계)

  • GIAP, VAN-TIEN;LEE, YOUNG DUK;KIM, YOUNG SANG;QUACH, THAI QUYEN;AHN, KOOK YOUNG
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.4
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    • pp.303-311
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    • 2019
  • Reversible solid oxide fuel cell (RSOFC) has become a prospective device for energy storage and hydrogen production. Many studies have been conducted around the world focusing on system efficiency improvement and realization. The system should have not only high efficiency but also a certain level of simplicity for stable operation. External waste steam utilization was proved to remarkably increase the efficiency at solid oxide electrolysis system. In this study, RSOFC system coupled with waste steam was proposed and optimized in term of simplicity and efficiency. Ejector for fuel recirculation is selected due to its simple design and high stability. Three system configurations using ejector for fuel recirculation were investigated for performance of design condition. In parametric study, the system efficiencies at different current density were analyzed. The system configurations were simulated using validated lumped model in EBSILON(R) program. The system components, balance of plants, were designed to work in both electrolysis and fuel cell modes, and their off-design characteristics were taken into account. The base case calculation shows that, the system with suction pump results in slightly lower efficiency but stack can be operated more stable with same inlet pressure of fuel and air electrode.

Prediction and optimization of hydrogen yield and energy conversion efficiency in a non-catalytic filtration combustion reactor for jet A and butanol fuels

  • Shabanian, Seyed Reza;Edrisi, Sanaz;Khoram, Fatemeh Vahdat
    • The Korean Journal of Chemical Engineering
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    • v.34 no.8
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    • pp.2188-2197
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    • 2017
  • Hydrogen production is one of main subjects in fuel cells. The traditional method of synthesis gas production is based on fuel reforming using catalysts. The main problem of these methods is sensitivity and fast degradation of catalysts especially when fuels with high sulfur content are used. A new technique for hydrogen production is fuel-reforming using non-catalytic filtration combustion in porous media reactors. Various experimental works have been carried out to increase hydrogen production under different operating conditions such as inlet fuel velocity and equivalence ratio. First, we investigated the ability of adaptive neuro fuzzy inference system (ANFIS) for predicting the filtration combustion characteristics. Four distinct ANFIS models were developed for estimating the hydrogen yield and energy conversion efficiency for fuels of jet A and butanol. Eight different membership functions of dsigmf, gauss2mf, gaussmf, gbellmf, pimf, psigmf, trapmf and trimf were tested for training of the ANFIS networks. The results showed that the RMSE of the best developed ANFIS models for estimating of the hydrogen yield of jet fuel, hydrogen yield of butanol, conversion efficiency of jet fuel and conversion efficiency of butanol were 1.399, 1.213, 0.508 and 2.191, respectively. Moreover the $R^2$ values of 0.998, 0.998, 0.999 and 0.999 were obtained for predicting the above mentioned variables, respectively. In the second step, a novel algorithm based on imperialist competitive algorithm (ICA) was used for optimization of hydrogen yield and energy efficiency. The maximum value of hydrogen yield and energy efficiency was 50.46% and 67.88% for jet A and 47.27% and 96.93% for butanol, respectively. The results showed that the imperialist competitive algorithm is an efficient and powerful algorithm to optimize combustion processes.

Estimation of GHG Emissions Reduction and Fuel Economy Improvement of Heavy-Duty Trucks by Using Side Skirt and Boat Tail (사이드스커트와 보트테일을 이용한 대형화물차량의 연비개선 효과 및 온실가스 감축량 추정)

  • Her, Chul haeng;Yun, Byoeng gyu;Kim, Dae wook
    • Journal of Climate Change Research
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    • v.7 no.2
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    • pp.177-184
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    • 2016
  • Recently, the need for technology development of commercial vehicle fuel consumption has emerged. Fuel economy improvement of transport equipment and transportation efficiency, and increasing attention to the logistics cost reduction measures. Increasing attention to the logistics cost reduction measures by fuel economy improvement of transport equipment and transportation efficiency. In this study, we have installed aerodynamic reduction device (side skirt, boat tail) to 14.5 ton cargo trucks and 45 ft tractor-trailers. And the fuel consumption was compared installed before and after. Fuel economy assessment for the aerodynamic reduction value device was tested by modifying the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test in according domestic situation. Greenhouse gas reductions were calculated in accordance with the scenario, including fuel consumption test results. When the 14.5 ton cargo trucks has been equipped with side skirts and boat tail, it confirmed the improvement in fuel efficiency of 4.72%. One Heavy-duty truck's the annual greenhouse gas reductions value are $6.86ton\;CO_2\;eq$. And if applying the technology to more than 50% of registered 15 ton trucks, greenhouse gas reductions are calculated as $686,826ton\;CO_2\;eq./yr$.

An Evaluation on the Combustion Characteristics of Heavy Oil-Water Emulsions (중질유-물 유화연료의 연소특성 평가)

  • Lee, Yong-Il
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.12
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    • pp.1722-1728
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    • 2002
  • Most researches regarding emulsified fuel were in the areas of emulsifier, emulsified fuel manufacturing and emulsified fuel droplet combustion, but there were little papers published regarding emulsified fuel combustion and boiler efficiency in an industrial boiler. The main purpose of this study is to clarify whether improvements in the boiler efficiency and the reduction of pollutants such as CO, NOx, SOx and smoke exist or not when emulsified fuels are combusted in the commercial boiler. Main experimental parameters were water content in heavy oil , excess $O_2$, and boiler load. The fuels used in this experiment were 0.5 B-C, and 5 kinds of 0.5 B-C/water emulsified fuels. The combustion characteristics of heavy oil and its emulsions with water were investigated in an industrial boiler. The combustion stability was monitored and exhaust gases such as CO, NOx, SOx and smoke were measured with excess $O_2$ and combustion load. In case of emulsified fuel combustion, flame stability was poor and boiler efficiency was lowered by 1.6~5.7%, but emission levels of CO and smoke were improved.