• Journal of Environmental Science International
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• v.27 no.6
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• pp.437-445
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• 2018

Laser induced-exciplex-fluorescence (EXCIPLEX) proposed by Melton is used to visualize fuel vapor in spray combustion. However, in the EXCIPLEX method based on TMPD/naphthalene system, the TMPD : naphthalene ratio is strictly restricted to 1 : 9. In addition, fluorescence intensity due to the vapor phase is extremely weak. To overcome these drawbacks, we propose a new laser-induced-excimer fluorescence (EXCIMER) method to visualize the liquid and vapor phases simultaneously. The spatial distributions of liquid and vapor in fuel spray suspended by ultrasonic waves are compared using the EXCIPLEX and EXCIMER methods. The correlation between fuel vapor concentration and fluorescence intensity is experimentally investigated by measuring the fluorescence intensity of saturated vapor formed over liquid fuel at a controlled temperature. These experimental results indicate that the EXCIMER method is effective for evaluating fuel vapor visualization in spray combustion. Furthermore, the quantitative distribution of fuel vapor concentration can be correctly estimated by the EXCIMER method.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.31-36
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• 2007

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Hydrogen Fuel is injected in the cavity parallel with air(or nitrogen fuel) flow. The equivalence ratios in this study are 0.132 and 0.447. Experimental measurements use OH-PLIF near the cavity and pressures in the combustor. For parallel fuel injection case, direct fuel add into cavity leads to increase of cavity pressure. And Flame exists just near the bottom wall for low equivalent ratio. There is no flame in the cavity because of no mixing in it. Compared to the inclined fuel injection, ignition delay length is longer for low equivalence ratio in both case. OH distribution is not a single line but a repeatable fluctuation flame structure by turbulence. Pressure distributions have nothing to do with the fuel injection position.

• Journal of the Korean Society of Combustion
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• v.14 no.2
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• pp.18-25
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• 2009

Fuel lean reburning method is very attractive way in comparison with conventional reburning method for reducing NOX. Meanwhile, the knowledge of the how flue gas re-circulated, temperature distribution and species concentration is crucial for the design and operation of an effective fuel lean reburning system. For this reason, numerical analysis of fuel lean reburning system is a very important and challenge task. In this work, the effect of fuel lean reburn system on NOX reduction has been experimentally and numerically conducted. Experimental study has been conducted with a 15kW lab scale furnace. Liquefied Petroleum Gas is used as main fuel and reburn fuel. To carry out numerical study, the finite-volume based commercial computational fluid dynamics (CFD) code FLUENT6.3 was used to simulate the reacting flow in a given laboratory furnace. Steady state, three dimensional analysis performed for turbulent reactive flow and radiative heat transfer in the furnace.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1373-1375
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• 1994

We now expect the various dispersed generation system installation to the power distribution system in a unexpected manner. If so, the power utility may experience the several unexpected problems such as voltage variation, harmonic distortion etc. In order to test the various phenomena related to the fault, we developed the fuel cell simulator and fault simulator. Several kinds of fault cases are tried. Test results and analysis are shown in this paper.

• Nuclear Engineering and Technology
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• v.34 no.5
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• pp.482-493
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• 2002

The MOX fuel for LWR is fabricated either by direct mechanical blending of UO$_2$ and PuO$_2$ or by two stage mixing. Hence Pu-rich particles, whose Pu concentrations are higher than pellet average one and whose size distribution depends on a specific fabrication method, are inevitably dispersed in MOX pellet. Due to the inhomogeneous microstructure of MOX fuel, the thermal conductivity of LWR MOX fuel scatters from 80 to 100 % of UO$_2$ fuel. This paper describes a mechanistic thermal conductivity model for MOX fuel by considering this inhomogeneous microstructure and presents an explanation for the wide scattering of measured MOX fuel＇s thermal conductivity. The developed model has been incorporated into a KAERI＇s fuel performance code, COSMOS, and then evaluated using the measured in-pile data for MOX fuel. The database used for verification consists of homogeneous MOX fuel at beginning-of-life and inhomogeneous MOX fuel at high turnup. The COSMOS code predicts the thermal behavior of MOX fuel well except for the irradiation test accompanying substantial fission gas release. The over-prediction with substantial fission gas release seems to suggest the need for the introduction of a recovery factor to a term that considers the burnup effect on thermal conductivity.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.554-557
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• 2008

In this study, two types of central flow distributor designs are presented and compared to obtain the optimal compact design which has the least flow resistance and the uniform flow distribution in a vehicular fuel cell stack. For effective and reliable prediction on the thermo-flow characteristics of the reactants flow over the entire fuel cell stack domain, open channel flow in the bipolar plates of the power generating cells were simulated by applying a simplified flow resistance model with an empirical porous concept. A number of case studies were performed to figure out an optimal configuration of a central flow distributor device in terms of the time-dependent thermo-flow behavior and load-dependent flow distribution. The results showed that the stable and load-independent thermo-flow uniformity is very design specific, which is closely associated with the design of central manifolding devices in order to achieve the enhanced volumetric power density and the reliable long-lasting operating of fuel cells.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.97-100
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• 2007

Fuel Cell Stack performance, which is influenced by the maintenance of a constant internal environment, requires high levels of air tightness. Used for analysis, gasket for fuel cell is made of elastic rubber materials and placed over separator, and shape of deformation of a gasket affects the transformation separator and airtightness while fastening structure. Separator as made of steel sheet isn't broken under pressure but can affect gas and cool water flow by the plastic deformation process. Therefore， it is understood that assembly process is well developed in case distribution of stress and shape of deformation is shown uniformly. This study is conducted on the assumption that a fuel cell maintenance is advantageous in that conditions. In this paper, analyses of unit cell and partial model were performed and distribution of stress and shape of deformation of Gasket and separator were analyzed to evaluate the airtightness while fastening structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.173-178
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• 2003

The study was performed to understand combustion characteristics of the slinger combustor. Liquid fuel is discharged radially outwards through injection holes drilled in the high speed rotating shaft. We observed atomizing characteristics with variation of fuel nozzle rotating speed by using PDPA system. The mean drop diameter highly depends on fuel nozzle rotating speed. In KARI combustion test facility, Ignition and combustion tests were performed by using real scale combustor. In the test results, ignition and combustion efficiency were increased according to increasing fuel nozzle rotating speed. The measured radial temperature distribution at the combustor exit shows stable and fairly good distribution.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.5
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• pp.186-194
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• 2016

As a turbulence-enhancing device, a mixing vane installed at a spacer grid of the fuel assembly plays a role in improving the convective heat transfer by generating either swirl flow in the subchannels or cross flow between fuel rod gaps. Therefore, both configuration and arrangement pattern of a mixing vane are important factors that determine the performance of a mixing vane. In this study, in order to examine the flow distribution features inside $5{\times}5$ fuel assembly with swirl-type mixing vanes used in benchmark calculation of OECD/NEA, simulations were conducted with commercial CFD software ANSYS CFX R.14. Predicted results were compared to data measured from MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels-Horizontal) test facility. In addition, the effect of swirl-type mixing vanes on flow pattern inside the fuel assembly was described.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.963-972
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• 2003

Performance characteristics of the planar-type solid oxide fuel cell (SOFC) are investigated by the analysis of flow fields coupled with heat and mass transfer phenomena in anode and cathode channels. For these purposes, performance analysis of the SOFC is conducted based on electrochemical reaction phenomena in electrodes and electrolyte coupled with flow fields in anode and cathode channels. In the present study, the isothermal model adopted in the previous paper prepared by the same authors is extended to the non-isothermal model by solving energy equation additionally with momentum and mass transfer equations using CFD technique. It is found that the difference between isothermal and non-isothermal models come from non-uniform temperature distribution along anode and cathode electrodes by solving energy equation in non-isothermal model. Non-uniform temperature distribution in non-isothermal model contributes to the increase of average temperature of the fuel cell and influences its performance characteristics.