• Clean Technology
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• v.17 no.4
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• pp.336-345
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• 2011

The total area of forest land in Korea is 64.2%, and significant forest resources can continuously be produced. However our country didn't separate the recyclable waste wood and was illegal landfill or incinerated. In this study, waste-wood and rice husk of biomass and low-grade-anthracite made refuse derived fuel by mixing and compressing. In addition, the binding effect of binders and additives were analyzed. Physical and chemical characteristics of manufactured refuse derived fuel were analyzed and evaluated suitability by compared with quality standards. A result of change with compressed and relaxed density, added 20% anthracite and 10% rice husk is optimal density change and average density increased large range when 20 wt.% P.V.A., guargum, molasses and 10 wt.% starch were added. All fuel samples be distributed over 3,500 kcal/kg LHV and grade of No. 3~4 fuels appeared. A result of the characteristics of physical and chemical compressed biomass refuse derived fuel with addictive, 12.9% of durability improvement appeared when is mixing asphalt and 5.8% of durability improvement appeared when is mixing rice bran by pretreatment of NaOH 5%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.274-280
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• 2005

Experimental investigations were carried out in an atmospheric pressure, optically accessible and laboratory-scale dump combustor. The objective of this study is to obtain the phase-resolved gas temperatures at different phases of the oscillating pressure cycle during unstable combustion. To see the effect of incomplete fuel-air mixing on phase-resolved temperature characteristics, CARS temperature measurements were performed. Results including phase-resolved averaged temperature, normalized standard deviation and temperature probability distribution functions (PDFs) were provided in this paper. It could be found that the profile of mean temperature showed the in-phase relationship with pressure cycle. Temperature PDFs give an insight on the flame behavior as well as NOx emission characteristics. These results would be expected to play an important role in better understanding of driving mechanisms and thermo-acoustic interactions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.840-843
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• 2002

The dry pulverizing/Mixing device is used to deal with the spent fuels for the safe disposal. The separated pellets from hulls by a slitting device are put and oxidized from UO$_2$ solid pellet to U$_3$O$\_$8/ powder in the device. The device have been developed based on a voloxidation method which is one of several dry de-cladding methods. We have benchmarked dry de-cladding methods, analyzed applicability to the advanced spent fuel management process, integrated and compared several configuration, and finally derived detailed specifications proper to requirements for the device. Also, thermal characteristics of the device such as thermal stress and strain have been analyzed by the commercial software, 1-DEAS, and the reliability of the results have been verified by the KOLAS(Korea Laboratory Accreditation Scheme). The UO$_2$ solid pellets are put in the device which has a capacity of 20 kgHM per a batch, heated up about 600$^{\circ}C$ in the air environment. Then, the UO$_2$ solid pellets are oxidized into the U$_3$O$\_$8/ powder, and the powder is collected in a special vessel. The device has been designed and developed as fellows: the multi-staged fine hole meshes are used to reduce the size of the powder gradually, heat and air(oxygen) are supplied continuously to reduce the reaction time, and slight vibration effect are applied to collect powder cling to the device.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1108-1114
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• 2007

The effect of oxidizer injection angle on the combustion characteristics of end-burning hybrid combustor is numerically investigated. Besides the previously studied parameter(injector arrangement, port diameter and O/F ratio), three different injection angle are considered: parallel angle to fuel surface(Case 1), +30 degree inclined angle toward the fuel(Case 2) and 30 degree inclined angle toward the nozzle(Case 3). It is found that Case 2 has the best mixing pattern in the upstream area but has the worst combustion efficiency since non negligible amount of unburned fuel is expelled from the nozzle. In contrast, though Case 1 and Case 3 showed relatively low mixing effect than the Case 2, they had high combustion efficiency. The comparison of numerical results between Case 1 and Case 3 demonstrate that no major difference is encountered, however, Case 1 is expected to have the best combustion efficiency due to the low residence time of the Case 3 injector which heads toward the nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.437-444
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• 2005

Experiments were carried out in an atmospheric pressure, lab-scale gas turbine combustor to see the effect of partial premixing on unstable flame structure and Nox emission characteristics. The swirl angle is 45 deg., fuel-air mixing degrees were varied 0, 50 and 100% respectively at equivalence ratio ranging from 0.53 to 0.79. The evolution of phased-locked OH chemiluminescence images were acquired with an ICCD. NOx emission characteristics were also investigated at each experimental condition. The effect of the fuel-air mixing degree on the flame structure was obtained from phase-locked $OH^*$ images. And it was obtained from local heat release characteristics that the information about the region which the combustion instability was amplified or damped. It also could be confirmed that $\sigma$ has greatly influence on NOx emission characteristics at lean regimes. It would be expected that it could provide invaluable data for understanding the mechanism of combustion instability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.62-68
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• 2005

An injector for fuel rich gas generator was designed and experimentally investigated. Five variations of F-O-F triplet impinging type injector were tested to evaluate spray characteristics with kerosene/water simulant propellant. Test was focused to find the effect of design variables of impinging angle, and impinging distance, on the atomization performance. A mixing efficiency is used to compare droplet distribution and local O/F ratio of each injector in the range of momentum ratio of 0.2~1.3. Test results shows the max value of mixing efficiency locates about the 0.8 in momentum ratio. And the injector with an impinging angle of 45 degree and impinging distance of 6mm shows the very good performance result suitable for fuel rich gas generator. A combustion test will be also conducted with selected injector to verify the spray pattern and mixing efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.917-922
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• 2015

The goal of this study is to consider the application of alternative blended fuel to diesel engine. In this study, as the test fuels, we use a blended fuel mix of diesel and hydrogen peroxide. As the primary variable, we vary the mixing ratio of diesel and hydrogen peroxide in the experimental and numerical analysis. We perform an evaporative behavior characteristics analysis of the emulsified fuel using the Schlieren method. The numerical analysis was carried out based on results obtained from the experimental analysis using the commercial code(ANSYS CFX). Consequently, we found that the micro-explosion depends on the fraction of hydrogen peroxide, and we propose a numerical method for the quantitative evaporation analysis of emulsified fuel droplets using the calculation of the volume fraction in the oil domain.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.1-9
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• 2014

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of petroleum fuels. Fast pyrolysis of biomass is one of several paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO) has been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of WPO in a diesel engine requires modifications due to low energy density, high water contents, high acidity, high viscosity, and low cetane number of the WPO. One possible method by which the shortcomings may be circumvented is to co-fire WPO with other petroleum fuels. WPO has poor miscibility with light petroleum fuel oils; the most suitable candidates fuels for direct fuel mixing are methanol or ethanol. Early mixing with methanol or ethanol has the added benefit of significantly improving the storage and handling properties of the WPO. For separate injection co-firing, a WPO-ethanol blended fuel can be fired through diesel pilot injection in a dual-injection dieel engine. In this study, the performance and emission characteristics of a dual-injection diesel engine fuelled with diesel (pilot injection) and WPO-ethanol blend (main injection) were experimentally investigated. Results showed that although stable engine operation was possible with separate injection co-firing, the fuel conversion efficiency was slightly decreased due to high water contents of WPO compare to diesel combustion.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.897-907
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• 2020

The flow characteristics of reactor fuel assembly always intrigue the designers and the experimentalists among the myriad phenomena that occur simultaneously in a nuclear core. In this work, the visual experimental method has been developed on the basis of refraction index matching (RIM) and particle image velocimetry (PIV) techniques to investigate the detailed flow characteristics in China fast reactor fuel subassembly. A 7-rod bundle of simulated fuel subassembly was fabricated for fine examination of flow characteristics in different subchannels. The experiments were performed at condition of Re=6500 (axial bulk velocity 1.6 m/s) and the fluid medium was maintained at 30℃ and 1.0 bar during operation. As for results, axial and lateral flow features were observed. It is shown that the spiral wire has an inhibitory effect on axial flow and significant intensity of lateral flow mixing effect is induced by the wire. The root mean square (RMS) of lateral velocity fluctuation was acquired after data processing, which indicates the strong turbulence characteristics in different flow subchannels.

• Nuclear Engineering and Technology
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• v.2 no.1
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• pp.19-25
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• 1970

A study was conducted on the coolant mixing between water flowing in two adjacent subchannels. Measurements were made of the quantity of mass transferred between a larger rectangular channel and a smaller triangular channel in a 19-rod fuel bundle under the conditions of single phase flow and air-water two-phase flow. The results of the experiments showed that the low mixing rate appears in single phase flow, and high mixing rate was measured in air-water two-phase flow Mixing rate decreases with the increasing of air void fraction during the air-water flow. It seems that the high mixing rate in the air-water flow was caused due to adequate agitation of the chaotic air void.