• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1939-1949
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• 2005

Many studies have been conducted to increase regression rate of solid fuel in hybrid rocket. One of them resorts to swirl flow since it can extend the residence time of oxidizer in the fuel grain. Also, metal wires may lead to increase the regression rate of solid fuel as shown in solid propellants. In this study, a series of experiments was designed to investigate the enhancement of regression rate of solid fuel by embedded metal wires and by fuel port grain. And fuel port was designed with a helical configuration to attempt to induce swirl flow. PMMA with gaseous oxygen is the solid fuel used for investigation. Test results showed that embedded metal wires turned out to be ineffective method because only $3-4\%$ increases in regression rate were observed. However, fuel port grain configuration yields higher burning performance of up to $50\%$ increase in regression rate. Also pitch number as well as total impulse was found to be a design variable.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.517-527
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• 1989

A theoretical analysis for the characteristics of pyrolysis and combustion of solid fuel was carried out in the present study. The hollow cylindrical combustion model including gas phase and solid fuel at inside and outside respectively was developed for the numerical analysis and parametric studies. The effects of volatile contents in the porous solid fuel and Reynolds number at inlet of gas phase on the characteristics of pyrolysis and combustion such as the radial, axial and time variations of volatile mass flux through porous solid fuel, temperature, mass fractions of gaseous fuel and oxidizer, and flame shape were investigated in the parametric studies. The results of the present study show that the flame produced by the volatiles moves to the downstream of fuel with accelerating velocity with time until extinction is occurred resulting from the completion of pyrolysis. When flame is employed with smaller amount of volatiles content in the solid fuel, the flame sheet exists closer to the inner wall of solid fuel. As Reynolds number at inlet increases, the flame sheet moves to the inner wall due to effect of convection even though the volatiles by pyrolysis increases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.3
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• pp.294-302
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• 1998

Ignition characteristics of a vertical solid fuel plate with block have been investigated experimentally. For low radiant heat flux, ignition does not occur in a vertical solid fuel plate without block. In the case with the block on a vertical fuel plate, however, ignition can occur by increasing the residence time and the time to absorb the incident radiation flux by fuel vapor in gas phase. The ignition occurs below block and the point varies according to the block location and the block height. As the block height increases, the block locates at higher position, and the hot wall temperature increases, the ignition delay time decreases. Also as the initial temperature of fuel plate rises, the ignition delay time of the solid fuel plate decreases. The temperature distribution of solid fuel plate with block is nearly proportional to the radiant heat flux distribution. Therefore, the effect temperature by natural convection heat transfer is of the same order as that of inhibition of temperature increase by pyrolysis.

• Environmental Engineering Research
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• v.23 no.4
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• pp.456-461
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• 2018

The solid-state anaerobic digestion (SS-AD) has promoted the development and application for biogas production from biomass which operate a high solid content feedstock, as higher than 15% of total solids. However, the digested byproduct of SS-AD can be used as a fertilizer or as solid fuel, but it has serious problems: high moisture content and poor dewaterability. The organic residue from SS-AD has to be improved to address these problems and to make it a useful alternative energy source. Hydrothermal carbonization was investigated for conversion of the organic residue from the SS-AD of livestock waste to solid fuels. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures within the range of $180-240^{\circ}C$. Hydrothermal carbonization increased the calorific value through the reduction of the hydrogen and oxygen contents of the solid fuel, in addition to its drying performance. Therefore, after the hydrothermal carbonization, the H/C and O/C atomic ratios decreased through the chemical conversion. Thermogravimatric analysis provided the changed combustion characteristics due to the improvement of the fuel properties. As a result, the hydrothermal carbonization process can be said to be an advantageous technology in terms of improving the properties of organic waste as a solid-recovered fuel product.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.286-288
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• 2007

The research and development for the solid oxide fuel cell have been promoted rapidly and extensively in recent years, because of their high efficiency and future potential. Therefore this paper describes the manufacturing method and characteristics of anode electrode for solid oxide fuel cell, by the way, Ni-YSZ materials are used as anode of solid oxide fuel cell widely. In order to reduce production costs, we have fabricated single solid oxide fuel cell by doctor blade and screen printing method. Disk-type planar solid oxide fuel cell with an effective electrode area of about $7cm^2$ were fabricated and run for 500 h to investigate cell performance. The current density at a voltage of 0.7 V was $850mA/cm^2$.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.751-757
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• 2006

Recently, a new type of solid oxide fuel cells has been developed employing extremely thin oxide electrolyte. These fuel cells are expected to operate at significantly reduced temperature compared to conventional solid oxide fuel cells. Accordingly, they may resolve the stability and material selection issues of high temperature fuel cells. Furthermore, they may eliminate the limitations of polymer membrane fuel cells whose operation temperature is under $100^{\circ}C$. In this paper, we review the electrolytes for intermediate temperature operation. Then, we discuss the current development of thin film solid oxide fuel cells that possibly operated at low temperatures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.233-236
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• 2007

In this paper, thermal sensitivity of the solid fuel grain in the hybrid rocket motor was investigated. When the heat from the non-reacting hot flow passing the grain ports is transferred to the solid fuel grain, the temperature fields in the solid fuel was numerically analyzed. These numerical analyzes were performed under the different nine port radii, and the critical distance between the ports in which the temperature in the solid fuel is sensibly responding was determined. Thus, the critical distance between the ports would be the important consideration for the design of the fuel grain because the high temperature in the fuel can bring the structural problems.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1629-1635
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• 2017

Reliable prediction of nuclear fuel rod behavior of nuclear power reactors constitutes a basic demand for steady-state calculations, design purposes, and fuel performance assessment. Perfect design of fuel rods as the first barrier against fission product release is very important. Simulation of fuel rod performance with a code or software is one of the fuel rod design steps. In this study, a software program called MARCODE is developed in MATLAB environment that can analyze the temperature distribution, gap conductance value, and fuel and clad displacement in both solid and annular fuel rods. With a comparison of the maximum fuel temperature, fuel average temperature, fuel surface temperature, and gap conductance in solid and annular fuel, the effects of a central hole on the fuel temperature distribution are investigated.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.865-871
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• 2005

Submicron thick solid electrolyte membrane is essential to the implementation of low temperature solid oxide fuel cell, and, therefore, development of new electrode structures is necessary for the submicron thick solid electrolyte deposition while providing functions as current collector and fuel transport channel. In this research, a nickel membrane with multi-stage nano hole array has been produced via modified two step replication process. The obtained membrane has practical size of 12mm diameter and $50{\mu}m$ thickness. The multi-stage nature provides 20nm pores on one side and 200nm on the other side. The 20nm side provides catalyst layer and $30\~40\%$ planar porosity was measured. The successful deposition of submicron thick yttria stabilized zirconia membrane on the substrate shows the possibility of achieving a low temperature solid oxide fuel cell.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.38-44
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• 2007

This paper describes the structural safety of solid fuel in the Hybrid Rocket Motor (HRM). Hybrid rocket combustion has the distinct regression characteristics which include the process of thermal pyrolysis and fuel vaporization. Most of all, this regression characteristics would structurally affect the strength of the fuel having a multi-port configuration, and even may cause the breaking from the fuel grain. This problem would probably influence the performance and operating safety of HRM. Therefore, for the safe operation of HRM, the critical port radius which determines the structurally safe region was discussed from the heat analysis of the solid fuel.