• Title, Summary, Keyword: Fuel efficiency

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Combustion Efficiency of Boron Carbide Fuel Solid Fuel Ramjet

  • Lee, Tae-Ho
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.722-725
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    • 2004
  • An experimental investigation was conducted to investigate the effects of the equivalence ratio and air mass flux on the combustion efficiency in a solid fuel ramjet used fuel grains which were highly loaded with boron carbide. Combustion efficiency increased with increasing equivalence ratio (grain length), and decreasing air mass flux. Higher inlet air temperature produced higher combustion efficiencies, apparently the result of enhanced combustion of the larger boron particles those bum in a diffusion controlled regime. Short grains which considered primarily of the recirculation region produced larger particles and lower combustion efficiencies. The result of the normalized combustion efficiency increased with inlet air temperature, is coincident with the result of the Brayton cycle thermal and the total efficiency relating to the heat input.

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DEVELOPMENT OF FUEL CELL HYBRID ELECTRIC VEHICLE PERFORMANCE SIMULATOR

  • Park, C.;Oh, K.;Kim, D.;Kim, H.
    • International Journal of Automotive Technology
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    • v.5 no.4
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    • pp.287-295
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    • 2004
  • A performance simulator for the fuel cell hybrid electric vehicle (FCHEV) is developed to evaluate the potentials of hybridization for fuel cell electric vehicle. Dynamic models of FCHEV's electric powertrain components such as fuel cell stack, battery, traction motor, DC/DC converter, etc. are obtained by modular approach using MATLAB SIMULINK. In addition, a thermodynamic model of the fuel cell is introduced using bondgraph to investigate the temperature effect on the vehicle performance. It is found from the simulation results that the hybridization of fuel cell electric vehicle (FCEV) provides better hydrogen fuel economy especially in the city driving owing to the braking energy recuperation and relatively high efficiency operation of the fuel cell. It is also found from the thermodynamic simulation of the FCEV that the fuel economy and acceleration performance are affected by the temperature due to the relatively low efficiency and reduced output power of the fuel cell stack at low temperature.

Transient Air-fuel Ratio Control of the Cylinder Deactivation Engine during Mode Transition (Cylinder Deactivation 엔진의 동작모드 전환 시 과도상태 공연비 제어)

  • Kwon, Min-Su;Lee, Min-Kwang;Kim, Jun-Soo;SunWoo, Myoung-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.2
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    • pp.26-34
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    • 2011
  • Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

Energy management strategies of a fuel cell/battery hybrid system using fuzzy logics (퍼지 논리를 이용한 연료전지/축전지 하이브리드 시스템의 운전제어)

  • Jeong, Kwi-Seong;Lee, Won-Yong;Kim, Chang-Soo
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.1
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    • pp.1-11
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    • 2004
  • Hybrid power systems with fuel cells and batteries have the potential to improve the operation efficiency and dynamic response. A proper load management strategy is important to better system efficiency and endurance in hybrid systems. In this paper, a fuzzy logic algorithm has been used to determine the fuel cell output power depending on the external required power and the battery state of charge(SoC). If the required power of the hybrid system is small and the SoC is small, then the greater part of the fuel cell power is used to charge the battery pack. If the required power is relatively big and the SoC is big, then fuel cell and battery are concurrently used to supply the required power. These IF-THEN operation rules are implemented by fuzzy logic for the energy management system of hybrid system. The strategy is evaluated by simulation. The results show that fuzzy logic can be effectively used to optimize the operational efficiency of hybrid system and to maintain the battery SoC properly.

Efficiency Improvement of Synchronous Boost Converter with Dead Time Control for Fuel Cell-Battery Hybrid System

  • Kim, Do-Yun;Won, Il-Kuen;Lee, Jung-Hyo;Won, Chung-Yuen
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.1891-1901
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    • 2017
  • In this paper, optimal control of the fuel cell and design of a high-efficiency power converter is implemented to build a high-priced fuel cell system with minimum capacity. Conventional power converter devices use a non-isolated boost converter for high efficiency while the battery is charged, and reduce its conduction loss by using MOSFETs instead of diodes. However, the efficiency of the boost converter decreases, since overshoot occurs because there is a moment when the body diode of the MOSFET is conducted during the dead time and huge loss occurs when the dead time for the maximum-power-flowing state is used in the low-power-flowing state. The method proposed in this paper is to adjust the dead time of boost and rectifier switches by predicting the power flow to meet the maximum efficiency in every load condition. After analyzing parasite components, the stability and efficiency of the high-efficiency boost converter is improved by predictive compensation of the delay component of each part, and it is proven by simulation and experience. The variation in switching delay times of each switch of the full-bridge converter is compensated by falling time compensation, a control method of PWM, and it is also proven by simulation and experience.

Construction of Map for Transient Condition of a Sl Engine and Refinement of Intake Air Model & Fuel Model (가솔린 엔진의 비정상 상태에 대한 Map 구성과 공기 및 연료 모델 개선)

  • 심연섭;강태성;강승표;고상근
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.1-8
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    • 2002
  • For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.

A Study on The Performance and Fuel Economy of Diesel Vehicles According to Change in Fuel Properties (연료물성에 따른 경유 차량의 성능 및 에너지소비효율 연구)

  • Noh, Kyeong-Ha;Lee, Min-Ho;Kim, Ki-Ho;Lee, Jung-Min
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.3
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    • pp.667-675
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    • 2018
  • Increasing emissions regulations and demand of high-efficiency cars that travels a lot of distance with less fuel, there is growing interest in Energy Consumption Efficiency. Korean energy consumption efficiency compute combined Fuel Economy by driven city & highway driving mode and present final Energy Consumption Efficiency as using 5-cycle correction formula. Energy consumption efficiency is computed Carbon-balance-method, when used burning fuel play a key role in vehicle performance & Energy Consumption Efficiency. In Korea, vehicle fuel is circulate by Petroleum and Petroleum Alternative Business Act, there is property difference in quality standard because petroleum sector's refine method or type of crude oil. It does not appear a big difference according to fuel, because it sets steady quality standard, it may affect the performance of automobile. Thus, in research We purchase a few diesel fuel which circulated in the market in summer season though directly-managed-gas station by petroleum sector, resolve property each of fuel, we compute Fuel Economy each of them. We analyze into change depend on applying for property as nowadays utilizing Energy Consumption Efficiency calculating formula of gasoline and diesel fuel. As result, Density each of sample fuel has a maximum difference roughly 0.9%, net heat value each of sample fuel has difference 1.6%, result of current Energy Consumption Efficiency each of sample fuel has a difference roughly 1% at city drive mode, 1.4% at highway drive mode. Result of use gasoline calculator formula shows less 6% result than nowadays utilizing Energy Consumption Efficiency calculating formula, each of sample's Energy Consumption Efficiency shows maximum roughly 1.4% result in city & highway drive mode.

Analysis of GHG Reduction Potential on Road Transportation Sector using the LEAP Model - Low Carbon Car Collaboration Fund, Fuel Efficiency, Improving Driving Behavior - (LEAP 모형을 이용한 도로교통부문의 온실가스 감축잠재량 분석 - 저탄소차협력금제도, 연비강화, 운전행태개선을 중심으로 -)

  • Kim, Min wook;Yoon, Young Joong;Han, Jun;Lee, Hwa Soo;Jeon, Eui Chan
    • Journal of Climate Change Research
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    • v.7 no.1
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    • pp.85-93
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    • 2016
  • This study the efficiency of greenhouse gas reduction of 'low carbon car collaboration fund' and its alternative 'control of average fuel efficiency and greenhouse gas', and 'improving driving behavior' were analyzed by using LEAP, long term energy analysis model. Total 4 scenarios were set, baseline scenario, without energy-saving activity, 'low carbon car collaboration fund' scenario, 'fuel efficiency improving scenario', and 'improving driving behavior' scenario. The contents of analysis were forecast of energy demand by scenario and application as well as reduction of greenhouse gas emission volume, and the period taken for analysis was every 1 year during 2015~2030. Baseline scenario, greenhouse gas emission volume in 2015 would be 7,935,697 M/T and 13,081,986 M/T in 2030, increased 64.8%. The analysis result was average annual increase rate of 3.4%. The expected average annual increase rate of other scenarios was, 'low carbon car collaboration fund' scenario 1.7%, 'fuel efficiency improving' scenario 3.0%. and 'improving driving behavior' scenario 3.4%. and these were each 1.7%, 0.3%. 0.3% reduce from baseline scenario. The largest reduction was 'low carbon car collaboration fund' scenario, and there after were 'fuel efficiency improving scenario', and 'improving driving behavior' scenario.

The Relative Effects of Feedback Frequency and Specificity of Eco-IVIS on Fuel Efficiency and Workload (에코 드라이빙 피드백 제공 빈도와 구체성이 연비와 작업부하에 미치는 효과)

  • Lee, Kyehoon;Cho, Hangsoo;Oah, Shezeen;Moon, Kwangsu
    • Journal of the Korean Society of Safety
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    • v.30 no.6
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    • pp.132-138
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    • 2015
  • This study examined the relative effects of feedback frequency and specificity of Eco-IVIS(eco in-vehicle information system) on the fuel-efficiency and workload. Eighty participants randomly assigned into four experimental groups (high frequency/specific, high frequency/global, low frequency/specific, and low frequency/global feedback) and they drove 16.4Km motorway under the each feedback condition. The dependent variable were fuel efficiency and Drive Activity Load Index which measured participants' subjective ratings of driving workload. The results showed that high frequent feedback was more effective for increasing fuel-efficiency than low frequent feedback, however, there was no significant difference of fuel-efficiency between specific and global feedback. Although, overall DALI score was comparable among four experimental conditions, visual demand score was significant higher under the high frequent feedback condition than low frequent feedback.

Fuel Efficiency and Emission Characteristics on Aged Three-way Catalyst of LPG Vehicle (LPG 차량의 삼원촉매 노후화에 따른 연비 및 배출가스 특성)

  • Kang, Minkyung;Kwon, Seokjoo;Kim, Kiho;Seo, Youngho
    • Journal of ILASS-Korea
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    • v.21 no.3
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    • pp.137-143
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    • 2016
  • The LPG vehicles are being operated by commercial purposes generally such as taxis. Most of taxis have a long-mileage and a harsh driving pattern. These properties may accelerate aging of the three-way catalysts much faster than the passenger vehicles. Because of this background, it was analyzed the test result of fuel efficiency and emissions on the LPG-fueled light duty vehicle. It was selected for a LPG vehicle of ULEV level to measure the fuel efficiency and emissions of the aged three-way catalysts. And the aged three-way catalysts which was driven about 300,000km and 550,000km replaced on the test vehicle in consecutive order. As a result, The aged three-way catalysts generally had no effect on fuel efficiency result, and harmful exhaust emissions had been shown to increase in most of the test mode, even though it satisfied the regulation value on most test modes.