• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.57-59
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• 2015

A method to measure heating value of natural gas using sound velocity and thermal conductivity is proposed to solve the low heating value issues of imported natural gas in South Korea. Natural gas generally consists of methane, butane, ethane, and inert gases. Heating value changes as the gas material properties, such as density, wobbe index, etc., varies. It is highly important to measure heating values of natural gases accurately because measuring the heating value depends on the given natural gases' components. Therefore, sound velocity and thermal conductivity is measured to estimate indirectly heating value of Natural gas with their changed components.

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.1-5
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• 2015

In general, natural gas is used as GHP(Gas Engine Driven Heat Pump) fuel. On this study, the influences of different natural gas heating value on GHP were evaluated. As a result of engine test & field test using low heating value gas($9,800kcal/Nm^3$) as fuel, the engine power was reduced slightly, however the performance of start-up, the stability of operation and the characteristics of emission gas were almost similar. So it is considered that the normal operation of GHP is possible without any tuning when the low heating value($9,800kcal/Nm^3$) of natural gas was used as fuel.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.599-607
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• 2009

This study was conducted to derive the five correlations which could predict specific gravity(or heating value), compression factor, density, etc., if we know heating value or specific gravity only. To make a sufficient number of raw data for regression, SGERG EOS was modified into equation of heating value. Based on these raw data, five correlations were obtained and the uncertainties of the correlations were evaluated. The results showed that the uncertainties were near 0.1% in most conditions of natural gas and so the correlations could be used in natural gas industry and academic fields.

• 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 Mechanical Engineers B
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• v.26 no.2
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• pp.328-335
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• 2002

In this study, experiments were performed to investigate the characteristics of flame stabilization of the LFG mixing gas. LFG has merely half heating value compared with liquified natural gas but can be greatly utilized as a commercial fuel. In order to use LFG in practical combustors, Webbe Index and heating value of LFG mixing gas were adjusted by mixing LPG with LFG. The comparisons were conducted between CH$_4$and LFG mixing gas for searching the region of flame stabilization based upon the flame blowout at maximum fuel stream velocity. As a result, the flame stability of LFG mixing gas was not improved with that of CH$_4$in non-swirl and weak swirl diffusion flame. However, LFG mixing gas had wide flame stabilization region rather than CH$_4$with increasing ambient flow rate in strong swirl. It was also found that flame stability was affected by included quantity of inert gas such as CO$_2$in the weak swirl but by heating value of fuel in strong swirl.

• Analytical Science and Technology
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• v.7 no.3
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• pp.329-338
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• 1994

The retention behaviors of natural gas components were studied on a single column by gas chromatography. The dead time, $t_0$ was obtained by using extrapolation of homologous series to determine capacity factors. The plots of retention data for homologous series and carbon number at different temperatures were shown to converge into a single point, which point was determined as a dead time. The results of the effect of temperature on the column efficiency for n-butane exhibited the plate number, N incerased with temperature, but the resolution among the fast eluted components decreased. The adsorption enthalpy (${\Delta}H^0{_{ads}}$) for each component on 28% DC 200 stationary phase was determined, and in order to investigate the retention behaviors of natural gas components the regression analysis of log $t_R$, log k' and log ${\alpha}$ vs. van der Waals volume(Vw), molecular connectivity index(X) and hydrophobic fragmental constant(f) were carred out. Good correlation was found between log k' vs. Vw, and log k' vs. f. The correlations between the physical properties of natural gas and the physical parameters were investigated by the linear regression analysis. The relationships between Vw vs. molecular weight and heating value(${\Delta}H_{comb}$), X vs. boiling point, and f vs. molecular weight, boiling point and heating value exhibited the high correlation coefficient more than 0.99. Using the regression equation between the heating value of natural gas and Vw the predicted heating values from $C_6$ to $C_{10}$ showed good agreement with those reported in the literature within 0.2% relative error.

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.94-97
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• 2005

• 한국가스학회:학술대회논문집
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• 2005.05a
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• pp.210-210
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• 2005

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.28-33
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• 2015

In this study, a dual fuel engine fueled with natural gas and diesel was tested to investigate the effects of heating value variation of CNG fuel. CNG substitution rate which is defined as the ratio of CNG and diesel supplied in a heating value basis was fixed at 80%. The higher heating value was varied from $10,400kcal/Nm^3$ to $9,400kcal/Nm^3$ by mixing nitrogen gas with pure CNG and diesel fuel was injected at a fixed injection timing. The engine test results showed that thermal efficiency and power output were decreased as the heating value of mixed CNG fuel was decreased. And the peak cylinder pressure was also decreased but the ignition delay time and the combustion duration and timing were almost same.

• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.6-10
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• 2006

In this study, gross heating value(GHV), density, vapor pressure and heat capacity of natural gas were estimated and their experimental data were compared with calculated ones, SRK method. A new alpha function was used to predict the vapor pressures of pure component of the natural gas constituents well instead of calculating vapor pressures with acentric factors. And binary adjustable parameters were determined by regressing binary vapor-liquid equilibria data. Through this study, our results showed good agreements with experimental data.