• Title, Summary, Keyword: Fuel efficiency

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A Simulation based Study on the Economical Operating Strategies for a Residential Fuel Cell System (시뮬레이션 기반 가정용 연료전지 시스템의 경제적 운전전략에 관한 연구)

  • Hwang, Su-Young;Kim, Min-Jin;Lee, Jin-Ho;Lee, Won-Yong
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.2
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    • pp.104-115
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    • 2009
  • In case of residential fuel cell system, it is significant to stably supply heat and power to a house with high efficiency and low cost for the successful commercialization. In this paper, the control strategy analysis has been performed to minimize the total cost including capital and operating cost of the residential fuel cell system. The proposed analysis methodology is based on the simulator including the efficiency models as well as the cost data for fuel cell components. The load control strategy is the key factor to decide the system efficiency and thus the cost analysis is performed when the fuel cell system is operated for several different load control logics. Additionally, annual efficiency of the system based on the seasonal load data is calculated since system efficiency is changeable according to the electric and heat demand change. As a result, the hybrid load control combined electricity oriented control and heat oriented control has the most economical operation.

Exhaust Emissions Characteristics of Bi-fuel CNG/LPG Passenger Cars (CNG/LPG Bi-fuel 승용차의 배출가스 특성)

  • Cho, Chong-Pyo;Lee, Young-Jae;Kim, Gang-Chul;Kwon, Oh-Seuk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.2
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    • pp.142-147
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    • 2011
  • Compressed natural gas (CNG) is well known as one of the cleanest burning alternative fuels. Bi-fuel CNG vehicle can also run on gasoline or another fuel while dedicated natural gas vehicle is designed to run on natural gas only. Recently, increased attention has been focused on bi-fuel CNG/LPG taxi because of good fuel economy of CNG. A number of LPG taxis modified to CNG Bi-fuel vehicles are running in many cities. In this paper, the emissions characteristics of in-use passenger cars running on CNG and LPG were investigated. Chassis dynamometer test was used to measure exhaust emissions from an in-use fleet of 5 cars. Exhaust emissions were collected for CVS-75 driving mode. The test results showed that for CNG fuel mode, CO, $CO_2$ and NMHC emissions decreased to 9%, 12% and 14% respectively, and $CH_4$ and $NO_x$ emissions increased to 317% and 47% respectively.

Power System of Fuel Cell Tram (연료전지궤도차량의 동력시스템)

  • Chang, Seky;Mok, Jai-Kyun;Lim, Tae-Hoon
    • Proceedings of the KSR Conference
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    • pp.320-325
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    • 2005
  • Power of fuel cell tram is supplied by only fuel cell system or hybrid system of fuel cell and battery/super capacity. Fuel cell is operated by hydrogen, which is fed directly from hydrogen tank or by reforming gasoline or methanol into hydrogen. Power system is preferred with hybrid of fuel cell and battery/super capacity since it improves total energy efficiency through interaction of hybrid components and restores energy regenerated by braking. Also, power supply system by fuel cell hybrid should be designed to output optimum energy efficiency depending on driving mode of fuel cell tram.

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Low price Fuel Cell Inverter System for 3[KW] Residential Power

  • Kwon, Soon-Kurl
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.4
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    • pp.61-72
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    • 2007
  • This study proposed a high efficiency DC-DC converter with a new current doubler rectifier for fuel-cell systems for use with the Nexa(310-0027) PEMFC from the Ballard Co. The proposed high efficiency DC-DC converter for the fuel-cell system generated ZVS by applying partial resonance and using a phase shift PWM control method. Constantly switching frequency, loss of switching, peak current, and peak voltage were reduced by this system. In addition to this system, two inductors were attached to a rectifier circuit allowing it to be able to provide the direct current(DC) and DC voltage safely to a load with reduced ripple components. Also, by using the newly proposed current doubler rectifier, the high frequency DC-DC converter for the fuel cell system was capable of reaching a highest efficiency of 92[%] as compared to 88.3[%] efficiency in previous results, which means that efficiency increased 3.7[%]. The overall results were confirmed by a simulation and laboratory experiment.

A Noval High Efficiency Grid Connected 1kW PCS for Fuel Cell (새로운 고효율 계통연계 1kW 연료전지용 PCS)

  • Kim, Tae-Jin
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.5
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    • pp.417-422
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    • 2008
  • In this paper, a novel DC/DC low-voltage high-current converter circuit is proposed to improve the efficiency of power converter used in the grid-connected fuel-cell generator system. We proposed a novel high efficiency grid-connected power conditioning system for RPG fuel cell. On the result of that, the loss of system was decreased rapidly by driving stack within the condition of maximum efficiency. The peak currents of the current-type inductor and the transformer's coil are reduced by synchronizing switching frequency of Buck-type converter is increased twice as the Push-Pull converter's switching frequency. The novel structure of DC/DC converter is able to realize ZVS-ZCS in fuel-cell system is proposed. The proposed switching component of Push-Pull converter has the ZVS and ZCS function by using the circuit of new passive clamp.

Operational Optimization of Anodic/cathodic Utilization for a Residential Power Generation System to Improve System Power Efficiency (가정용 연료전지 시스템의 전기 효율 향상을 위한 연료/공기 이용률 운전 최적화)

  • Seok, Donghun;Kim, Minjin;Sohn, Young-Jun;Lee, Jinho
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.5
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    • pp.373-385
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    • 2013
  • To obtain higher power efficiency of Residential Power Generation system(RPG), it is needed to operate system on optimized stoichiometric ratios of fuel and air. Stoichiometric ratios of fuel/air are closely related to efficiency of stack, reformer and power consumption of Balance Of Plant(BOP). In this paper, optimizing stoichiometric ratios of fuel/air are conducted through systematic experiments and modeling. Based on fundamental principles and experimental data, constraints are chosen. By implementing these optimum values of stoichiometric ratios, power efficiency of the system could be maximized.

The effect of water addition on combustion efficiency in premixed flame (물添加가 豫混合火焰의 燃燒效率에 미치는 影響)

  • 김성환;오신규;채재우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.5
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    • pp.819-827
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    • 1987
  • The purpose of the present investigation is to examine the effect of water addition on combustion efficieny. In this research, fuel and additive water are injected into a burner in the form of vapors through separate needle valves, the flame temperature and concentrations of soot, CO and unburned hydrocarbons were measured in a premixed flame. The results are obtained to be: In the fuel lean region, the reduction rate of CO, soot and HC by water injection increases slightly, but there is no change in the combustion efficiency. On the other hand, in the fuel rich region, the reduction rate of CO, Soot and HC by water injection increases more than that of the fuel lean region. Accordingly, combustion efficiency increases.

Development of an evaluation method for nuclear fuel debris-filtering performance

  • Park, Joon-Kyoo;Lee, Seong-Ki;Kim, Jae-Hoon
    • Nuclear Engineering and Technology
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    • v.50 no.5
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    • pp.738-744
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    • 2018
  • Fuel failure due to debris is a major cause of failure in pressurized water reactors. Fuel vendors have developed various filtering devices to reduce debris-induced failure and have evaluated filtering performance with their own test facilities and methods. Because of the different test facilities and methods, it is difficult to compare filtering performances objectively. This study presents an improved filtering test and an efficiency calculation method to fairly compare fuel-filtering efficiency regardless of the vendor's filtering features. To enhance the reliability of our evaluation, we established requirements for the test method and had a facility constructed according to the requirements. This article describes the debris specimens, the amount of debris, and the replicates for the proposed test method. A calculation method of comprehensive debris-filtering efficiency using a weighted mean is proposed. The test method was verified by repeated tests, and the tests were carried out using the PLUS7 and 17ACE7 test fuels to calculate the comprehensive debris-filtering efficiencies. The evaluation results revealed that the filtering performance of PLUS7 is better than that of 17ACE7. The proposed method can be used on any kind of debris-filtering devices and is appropriate for use as a standard.

A Study on the Influence of Test Temperature & Cooling Fan Condition on the Fuel Test of Diesel Vehicle (디젤차량 연비시험에 있어 시험온도 및 냉각팬 조건이 미치는 영향분석에 관한 연구)

  • Kim, Hyun-Jin;Kim, Sung-Woo;Lim, Jae-Hyuk;Noh, Kyung-ha;Lee, Jung-Cheon;Kim, Ki-Ho;Oh, Sang-Gi
    • Journal of the Korea Society For Power System Engineering
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    • v.21 no.6
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    • pp.46-55
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    • 2017
  • Due to the arise of natural disasters caused by global warming, consumers have more interest in the fuel efficiency of their vehicles, and fuel efficiency became an important factor in comparing vehicles. In this market situation, methods to measure fuel efficiency has become one of the main interests of vehicle related organizations and laboratories, and the current method to measure fuel efficiency is to follow the notification established by the ministry of trade, industry and energy, ministry of environment, and the ministry of land, infrastructure and transport. In this study, we analyze the influence of vehicle fuel efficiency according to test temperature and cooling fan condition which have the possibility to cause difference in fuel efficiency. The analysis results of the influence of the fuel efficiency according to the test temperature, the difference of the fuel efficiency of the test temperature ($21{\sim}29^{\circ}C$) within the allowable range of the notification showed a maximum difference of 2.9%. Therefore, it is necessary to consider the introduction of a test method that permits only the temperature change based on the reference point as the allowable range even in the test within the allowable range. The analysis of the influence of the fuel efficiency according to the cooling method showed no significant effect, and it seems reasonable to maintain the test method of the current notification.

A Power Control Scheme of a Fuel Cell Hybrid Power Source

  • Song, Yu-Jin;Han, S.B.;Park, S.I.;Jeong, H.G.;Jung, B.M.;Kim, G.D.;Yu, S.W.
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.183-187
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    • 2008
  • This paper describes a power control scheme to improve the performance of a fuel cell battery hybrid power source for residential application. The proposed power control scheme includes a power control strategy to control the power flow of the fuel cell hybrid power system and a digital control technique for a front-end dc-dc converter of the fuel cell. The power control strategy enables the fuel cell to operate within the high efficiency region defined by the polarization curve and efficiency curve of the fuel cell. A dual boost converter with digital control is applied as a front-end dc-dc converter to control the fuel cell output power. The digital control technique of the converter employs a moving-average digital filter into its voltage feedback loop to cancel the low frequency harmonic current drawn from the fuel cell and then limits the fuel cell output current to a current limit using a predictive current limiter to keep the fuel cell operation within the high efficiency region as well as to minimize the fuel cell oxygen starvation.

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