• Journal of ILASS-Korea
• /
• v.27 no.2
• /
• pp.66-76
• /
• 2022

This study presents a prediction methodology of transport properties using the methane-based TRAPP (m-TRAPP) method in a wide range of temperature and pressure conditions including both subcritical and supercritical regions, in order to obtain thermo-physical properties for hydrocarbon aviation fuels and their products resulting from endothermic reactions. The viscosity and thermal conductivity are predicted in the temperature range from 300 to 1000 K and the pressure from 0.1 to 5.0 MPa, which includes all of the liquid, gas, and the supercitical regions of representative hydrocarbon fuels. The predicted values are compared with those data obtained from the NIST database. It was demonstrated that the m-TRAPP method can give reasonable predictions of both viscosity and thermal conductivity in the wide range of temperature and pressure conditions studied in this paper. However, there still exists large discrepancy between the current data and established values by NIST, especially for the liquid phase. Compared to the thermal conductivity predictions, the calculated viscosities are in better agreement with the NIST database. In order to consider a wide range of conditions, it is suggested to select an appropriate method through further comparison with another improved prediction methodologies of transport properties.

• Journal of Aerospace System Engineering
• /
• v.14 no.4
• /
• pp.32-39
• /
• 2020

A technological review and analysis were performed on thermal cracking of aviation hydrocarbon fuels that circulate as coolants in regenerative cooling systems of hypersonic flights. Liquid hydrocarbons decompose into low-carbon-number hydrocarbons when they absorb a considerable amount of energy at extremely high temperatures, and these thermal cracking behaviors are represented by heat sink capacity, conversion ratio, reaction products, and coking propensity. These parameters are closely interrelated, and thus, they must be considered for optimum performance in terms of the overall heat absorption in the regenerative cooling system and supersonic combustion in the scramjet engine.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.3
• /
• pp.101-110
• /
• 2002

In this paper, the effects of oxygen component in blended fuel on the exhaust emissions have been investigated far direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for th? commercial diesel fuel and oxygenated blended fuels which have three kinds of fuels and various mixed rates. And, it was tried to analyze not only total hydrocarbon but individual hydrocarbons(C$_1$∼ C$\_$6/) in exhaust gases using gas chromatography to seek the reason far remarkable reduction of smoke emission on various oxygenated fuels. This study carried out by comparing the chromatogram with diesel fuel and diesel fuel blended DGM(diethylene glycol dimethyl ether), MTBE(methyl tart-butyl ether) and EGBE(ethylene glycol mono-n-butyl ether). The results of this study show that individual hydrocarbons as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with commercial diesel fuel.

• Journal of ILASS-Korea
• /
• v.6 no.3
• /
• pp.23-31
• /
• 2001

An experimental study was carried out to understand the spray characteristics of three kinds(kerosene, heating oil & diesel) of hydrocarbon-fuels. Fuel temperature and injection pressure were main variables in the experiment. Fuel Temperature was changed to obtain various levels of fuel viscosity. Spray angle and spray length were measured by using LVS(Laser Vapor Screen) photographs. 1D PDPA system was used to measure droplet size & droplet velocity. In room temperature, spray characteristics of three kinds of fuels were good, especially in case the fuel injection pressure was more than $6Kgf/cm^2$ It was also found that spray characteristics were poor in case fuel kinematic viscosity was more than 5cSt.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.15.2-15.2
• /
• 2005

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.4
• /
• pp.26-33
• /
• 2006

The use of high-density propellants can provide performance advantages in space launch vehicles by allowing an improved structural ratio due to smaller propellants tanks. The Jet A-1 fuel is currently used in Korean space launch vehicle development and it has lower density than other advanced hydrocarbon fuels such as RP-1 or RG-1. In this paper, the results of hydraulic and combustion tests conducted for the two newly developed densified hydrocarbon fuels are presented and they are compared with the results of Jet A-1. Conclusively, the two densified hydrocarbon fuels presented equivalent or even higher combustion performance compared to the Jet A-1 and the performance difference was found to be more obvious in the injector of external mixing.

• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.58-63
• /
• 2005

As fuel cells approach commercialization, hydrogen production becomes a critical step in the overall energy conversion pathway. Reforming is a process that produces a hydrogen-rich gas from hydrocarbon fuels. Hydrogen production via autothermal reforming (ATR) is particularly attractive for applications that demand a quick start-up and response time in a compact size. However, further research is required to optimize the performance of autothermal reformers and accurate models of reactor performance must be developed and validated. The design includes the requirement of accommodating a wide range of experimental set ups. Factors considered in the design of the reformer are capability to use multiple fuels, ability to vary stoichiometry, precise temperature and pressure control, implementation of enhancement methods, capability to implement variable catalyst positions and catalyst arrangement, ability to monitor and change reactant mixing, and proper implementation of data acquisition. A model of the system was first developed in order to calculate flowrates, heating, space velocity, and other important parameters needed to select the hardware that comprises the reformer. Predicted performance will be compared to actual data once the reformer construction is completed. This comparison will quantify the accuracy of the model and should point to areas where further model development is required. The end result will be a research tool that allows engineers to optimize hydrogen production via autothermal reformation.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.5
• /
• pp.1-9
• /
• 2011

Researches on hypersonic aircraft technologies have been carried out to increase flight speeds. However, increase in flight speeds causes heat loads that could lead structural change of aircraft's component. Researches on cooling technologies using endothermic fuels are progressing in the USA, France and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical condition of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.279-286
• /
• 2010

Hypersonic aircraft technologies have been developed with increase in flight speeds. As hypersonic flight speeds increase, heat loads on an aircraft and it's engine increase. Researches on cooling technologies using endothermic fuels are progressing in the USA, France, and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical phase of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.6
• /
• pp.560-566
• /
• 2015

HCCI (Homogeneous Charge Compression Ignition) hydrogen engine has relatively narrower operation range caused by knock occurrence due to the rapid pressure rising by using higher compression ratio. In this study, EGR as one of the countermeasure methods is considered to extend operation range of HCCI hydrogen engine. Also, the effects of hydrogen EGR are compared with the effects of EGR using hydrocarbon fuel. Hydrocarbon EGR is carried out by adding carbon dioxide to exhaust gas of HCCI hydrogen engine. As the results, EGR has positive effects on a HCCI hydrogen engine in reducing rate of pressure rise as same as the other engines used hydrocarbon fuels. However, the effects of hydrogen EGR are better than those of hydrocarbon EGR in decreasing minimum compression ratio and rate of pressure rise. When applying EGR to HCCI hydrogen engine by 20% rate, the rate of pressure rise decreases by 58% and it results in about 48% increase of the operation range in terms of supply energy.