• Applied Chemistry for Engineering
• /
• v.9 no.1
• /
• pp.76-81
• /
• 1998

Physical adsorption on a silica gel(pore size of 80 nm, particle size of $10{\mu}m$)has been studied for binary mixture of acetone diluted in $CO_2$ by use of a FTIR transmission technique and we have compared the result of FTIR transmission technique with that of a chromatographic technique. Measurements were made at 313.2 K and under pressures up to 15MPa. As the pressure increases from 0.1MPa, the IA(Integral Absorbance) of the hydrogen-bonded OH groups interacting with acetone and adsorbed amount by use of a chromatographic technique increases at first, and reaches a maximum at a pressure below the critical pressure of $CO_2$, and then the intensities decrease gradually with increasing pressure. It is found that the pressure dependency of the chromatographic isotherm is a little larger than that of spectroscopic isotherm in the supercritical fluid region. This difference might be attributable to the weaker van der Waals force and relatively stronger hydrogen-bonding force influencing the adsorption of acetone on the sllica gel. The unique spectroscopic characteristics of amine group which vibrational frequencies of hydroxyl groups on the silica gel surface shift downward to about $1300cm^{-1}$ were measured from experimental result of triethylamine diluted in $CO_2$ or $N_2$.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.3
• /
• pp.15-21
• /
• 2011

With petroleum reserves dwindling, interest has been increasing worldwide in Fischer-Tropsch synthesis (FT) as a method of producing synthetic liquid fuels and chemicals from coal, natural gas or biomass. In general, FT synthesis is operated through the gas phase fixed-bed reaction system. Recently, there are lots of study in supercritical fluid due to unique characteristics such as the quick diffusion of reactant gas, effective removal of reaction heat, and the in-situ extraction of high molecular weight hydrocarbon, such as wax. In this study, our major aim is to obtain a deeper insight into the effect of the type of support on the reaction performance over a supported cobalt catalyst in a fixed bed reactor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.150-155
• /
• 2010

Liquid rocket injectors play crucial roles on propulsive performance, combustion stability, and heat transfer characteristics. Nevertheless, their developments have mainly relied on empirical methods and expensive hot-firing tests due to lack of fundamental understanding of high pressure combustion phenomena in the near-injector regions. The present study was motivated by recent efforts to develop reliable modeling of liquid rocket combustion. The turbulent combustion model based on the flamelet concept has been extended to take into account real-fluid behaviors occurred at supercritical pressures, and validated against measurements for a cryogenic nitrogen injection, a non-premixed turbulent jet flame at atmospheric pressure, and a LOx/$GH_2$ coaxial shear injector at a supercritical pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.330-333
• /
• 2008

Present paper introduces the research activities on fuel-air mixing and combustion of supersonic turbulent flows in scramjet combustor carried out in Aerospace Combustion and Propulsion Laboratory of the department of Aerospace Engineering of the Pusan national University. Also, an introduction will be given to the characteristics of the supercritical hydrocarbon fuel combustion in a practical scramjet engine and its numerical modeling approaches.

• KSBB Journal
• /
• v.24 no.6
• /
• pp.533-540
• /
• 2009

In this work, 5'-nitroindirubinoxime (5'-NIO) has been prepared as solid dispersions using a supercritical aerosol solvent extraction system (ASES) process in order to enhance its water solubility and dissolution rate. Solid dispersions of 5'-NIO and poly(vinyl pyrrolidone) (PVP) were prepared in various weight percent ratios. Three-component solid dispersions consisting of 5'-NIO, PVP, and poloxamer 188 (P188) were also prepared to study the influence of P188 level on their morphology, crystallinity, and dissolution behavior. All samples were prepared at $35^{\circ}C$ and 180 bar using supercritical carbon dioxide. The particle morphology and size of the two-component solid dispersions were found to be nearly spherical and much smaller (100-200 nm) compared with the original 5'-NIO. The morphology of three-component solid dispersions became more agglomerated as the level of P188 increased. The crystallinity of the original 5'-NIO was not observed in the solid dispersions prepared by the ASES process. Faster dissolution rates were observed for the three-componet solid dispersions because the arrangement of ethylene oxide and propylene oxide blocks of the poloxamer 188 enabled the formation of micelles in an aqueous phase.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.5
• /
• pp.333-338
• /
• 2022

The single jet of decane/methylcyclohexane mixed fuel that is surrogate for kerosene was injected into supercritical environment and visualized using shadowgraph technique. The injection pressure drop of the fuel jet of T_r = 0.484 was kept constant at 0.5 MPa and the experiment was conducted above the critical point of the mixed fuel, and the reduced temperatures of the chamber was changed from 1.00 to 1.23, and the reduced pressures was 1.00 and 1.38. As an index for reducing the density of jets sprayed into the supercritical environment, the brightness intensity of the post-processed jet image was observed with the internal temperature and pressure of the chamber. It was confirmed that the decrease in the brightness intensity of the jet when the temperature inside the chamber increased, and when the pressure inside the chamber was higher at the same temperature, the decrease in the brightness intensity of the jet was delayed. When the pressure inside the chamber is high, it is thought that the change in brightness intensity is delayed due to the increase in the pseudo-critical temperature of the fuel and the increase in the temperature required to reduce the density of the fuel jet.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.3
• /
• pp.17-24
• /
• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.303-306
• /
• 2008

After the successful flight test of X-43A, U.S. Airforce is developing missile-type X-51A SED (Scramjet Engine Demonstrator-Wave Rider). X-51A using PWR (Pratt and Whitney Rocketdyne) X-1 hydrocarbon fueled scramjet engine will have a ground test in 2008 and flight test in 2009. Technologies established though the X-51A program will be transferred to DARPA's Falcon program developing HTV (Hypersonic Test Vehicle)-3X and HCV (Hypersonic Cruise Vehicle). Present paper is an overview of propulsion core technologies of X-51 such as regenerative cooling of engine structures and combustion using liquid/supercritical JP-7 fuel.

• 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.