• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3288-3293
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• 2007

Compressed natural gas has good potential for alternative vehicle fuel due to its economical and clean characteristics. However, the composition of natural gas based on production location is known to affect performance and emissions of CNG engine. Thus, the objective of this paper is to clarify the effect of fuel composition on combustion and emissions of CNG engine. This paper presents combustion characteristics obtained from running a 2.5L, 4-cylinder CNG engine retrofitted IDI diesel engine with engine dynamometer. BSFC, emissions, fuel consumption and combustion pressure were measured under steady state operating conditions especially at partial load for CNG engine. Based on the experimental results, we found that CNG composition affects engine performance, fuel conversion efficiency and burning rate.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.93-99
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• 2012

The investigation of clean and environment-friendly coal utilization technology is actively progressed due to high oil price and serious climate change caused by greenhouse gas emissions. In this study, the plasma gasification was performed using a 6kW microwave plasma unit under various reaction conditions: the particle sizes of coal ($45{\mu}m-150{\mu}m$), $O_2$/fuel ratio (0 - 1.3), and steam/fuel ratio (0 - 1.5). The $H_2$ composition decreases with decreasing coal particle size. With increasing $O_2$/fuel ratio, the $H_2$ composition in the syngas decreased while the $CO_2$ composition increased. As the steam/fuel ratio increased from 0 to 1.5, the $H_2$ composition in the syngas increased while the $CO_2$ composition decreased. From the results, it was proven that the variation of syngas composition greatly affected by $O_2$/fuel ratio than steam/fuel ratio. The $H_2$ composition in the syngas, carbon conversion, and cold gas efficiency increased with increasing plasma power.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.514-523
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• 2021

This study investigated the effect of anode fuel composition on the performance of direct borohydride/hydrogen peroxide fuel cells (DBHPFCs). The effect of sodium borohydride (NaBH₄) and sodium hydroxide (NaOH) concentrations on fuel cell performance was determined through fuel cell tests. Fuel cell performance increased with an increase in the NaBH₄ concentration, whereas it decreased with an increase in the NaOH concentration. The anode fuel composition was selected as 10 wt% NaBH₄+10 wt% NaOH+80 wt% H₂O based on the fuel viscosity, electrochemical reaction rate, and decomposition reaction rate. DBHPFCs were also tested to analyze the effect of operating temperature and operation time on fuel cell performance. The present results can be used as a reference basis to determine operating conditions of DBHPFCs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.4
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• pp.266-274
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• 2008

The need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as Liquefied Petroleum Gas(LPG) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a high vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to apply it for the conventional gasoline or diesel fuel pump directly. In this study, experiments are performed to get performance and efficiency of the fuel pump at different condition as temperature, rotating speeds, composition of fuel. The characteristics of fuel pump is affected by cavitation due to the variation of temperature and composition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1548-1562
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• 2003

This paper is the first of several companion papers which compare the methods of Air-fuel ratio determination. There are many methods which calculate Air-Fuel ratio from exhaust emission. Most of them are based on the simple chemical equations, which use balance of atom, and the error of the calculation is negligible as far as the instrumentation accuracy is guaranteed. They assume homogeneous mixture and complete combustion to the extent of oxygen availability. Because of these simple assumptions, they cannot offer the information about the fuel distribution state and the malfunction of instrument. For these limitations, Eltinge offered new one based on stricter mathematical model. This result coincides with the others very well and gives more information about the mixture state and instrumentation. Consequently this might be a general solution for Air-fuel ratio determination and exhaust composition. The objects of the calculation, however, were not commercial fuels except gasoline and the compensation method of unburned hydrocarbon was not appropriate to recent analyzer. Moreover he did not consider the fuel which contains oxygen, such as methanol, ethanol and blend of gasoline-alcohol. In this paper, Eltinge chart is expanded to the arbitrary fuel composition as the reference exhaust compositions for the purpose of further discussions about Air-fuel ratio determination methods and the charts fur gasoline, diesel, methanol, M85, liquefied petroleum gas(LPG), natural gas(NG), propane, butane are illustrated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1147-1154
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• 2004

This paper is the third of several companion papers which compare the method of Air-Fuel ratio determination. In the previous works, Eltinge chart was expanded to arbitrary fuel composition as a reference exhaust composition. The compensation of unburned hydrocarbon in Eltinge chart and comparison of Spindt and Eltinge method were also discussed. In addition to Eltinge and Spindt's one, however, there are many methods which calculate Air-Fuel ratio from exhaust emission. Among these methods, carbon balance and oxygen balance are widely used in practice. In some applications, linear formula from statistical method is being used in the field due to its simplicity and convenience. In this paper, these various methods are evaluated and compared with Eltinge results and new linear formula is proposed for the gasoline fuel. The results show that the corrected carbon balance equation has excellent agreement with Eltinge and Spindt's one. On the other hands, the oxygen-balanced formula has a limitation according to the mixture state and AFR. For gasoline fuel, newly proposed linear equation has good compatibility with Eltinge and Spindt up to AFR 17.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.566-575
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• 2011

Since LPG (Liquefied petroleum gas) fuel supply system has an advantage of low emission characteristics, many studies have been conducted. In spite of the advantage of LPG supply system, a higher vapor pressure and lower viscosity than diesel or gasoline fuel may cause unstable running of fuel pump by the deterioration in lubrication performance and chemical reaction with rubber parts than that of diesel and gasoline fuel. Therefore its physical properties can cause the deterioration of durability. In this research, we developed an external type LPG pump which has the advantage of the price competitiveness and the convenient maintenance for LPLi system. The experiments were carried out in order to assess characteristics of the external type fuel pump at different fuel composition and temperature. As a result, there aren't any differences between internal and external type pump performance. It is observed that the same level of efficiency was maintained for both pumps as flow rate was increased with higher fuel temperature and more contents of propane in the fuel. And the pressure difference in LPLi system is maintained at constant with the various fuel compositions and temperatures due to their own characteristics of fuel supply system.

• Journal of Mechanical Science and Technology
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• v.16 no.2
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• pp.219-226
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• 2002

Natural gas is considered to be a promising alternative fuel for passenger cars, truck transportation and stationary engines providing positive effects both on the environment and energy security. However, since the composition of natural gas fuel varies with location, climate and other factors, it is anticipated that such changes in fuel properties will affect emission characteristics and performance of CNG (Compressed Natural Gas) engines. The purpose of the present study is to investigate the effects of the difference in gas composition on the engine performance and emission characteristics. The results show that THC (Total Hydrocarbon) decreases with increasing Wl (Wobbe Index) and MCP (Maximum Combustion Potential). On the other hand, it is observed that NOx slightly increases as Wl and MCP increase. The TLHV (Total Lower Heating Value of Intake) is proposed in this study as a potential index for compatibility of gas fuels in a CNG engine. There is a variation in power up to 20% depending on the composition of gas when the A/F ratio and spark timing are flexed for a specific gas fuel.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.15-21
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• 2003

The liquid phase LPG injection engine is a new technology to make good use of LPG as a clean energy. However, it is difficult to precisely control air/fuel ratio in the system because of variation of fuel composition, change of temperature and flash boiling injection mechanism. This study newly suggests an injector control logic for liquid phase LPG injection systems. This logic compensates a number of effects such as variations of density, stoichiometric air/fuel ratio, injection delay time, injection pressure, release pressure which is formed by flash boiling of fuel at nozzle exit. This logic can precisely control air/fuel ratio with only two parameters of intake air flow rate and injection pressure without considering fuel composition, fuel temperature.

• Journal of Institute of Convergence Technology
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• v.3 no.2
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• pp.57-60
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• 2013

The purpose of this study is to analysis of how to calculate fuel efficiency in major development countries (U.S. and Europe) and energy consumption formular derivation of domestic CNG fuel and prove by vehicle test. The formula of fuel consumption is different in mpg(mile per gallon), l/100km, and km/l each countries. CNG fuel has a significant impact on fuel density, composition, and Hydro-Carbon ratio. So, this study how to measurement and calculation procedures of CNG gaseous fueled vehicle energy consumption rate.