• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.831-840
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• 2009

In order to evaluate the start-up behavior and to identify, through abnormal operation occurrences, the transient behaviors of the Sulfur Iodine(SI) process, which is a nuclear hydrogen process that is coupled to a Very High Temperature Gas Cooled Reactor (VHTR) through an Intermediate Heat Exchanger (IHX), a dynamic simulation of the process is necessary. Perturbation of the flow rate or temperature in the inlet streams may result in various transient states. An understanding of the dynamic behavior due to these factors is able to support the conceptual design of the secondary helium loop system associated with a hydrogen production plant. Based on the mass and energy balance sheets of an electrodialysis-embedded SI process equivalent to a 200 $MW_{th}$ VHTR and a considerable thermal pathway between the SI process and the VHTR system, a dynamic simulation of the SI process was carried out for a sulfuric acid decomposition process (Second Section) that is composed of a sulfuric acid vaporizer, a sulfuric acid decomposer, and a sulfur trioxide decomposer. The dynamic behaviors of these integrated reactors according to several anticipated scenarios are evaluated and the dominant and mild factors are observed. As for the results of the simulation, all the reactors in the sulfuric acid decomposition process approach a steady state at the same time. Temperature control of the inlet helium is strictly required rather than the flow rate control of the inlet helium to keep the steady state condition in the Second Section. On the other hand, it was revealed that the changes of the inlet helium operation conditions make a great impact on the performances of $SO_3$ and $H_2SO_4$ decomposers, but no effect on the performance of the $H_2SO_4$ vaporizer.

• Journal of the Korean institute of surface engineering
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• v.39 no.1
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• pp.25-34
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• 2006

Al-Mg alloy, an open rack vaporizer(ORV) material was reported to be corroded in seawater environments though the ORV material was coupled to thermally sprayed Al-Zn alloy functioning a sacrificial anode. In addition, the corrosion behavior based on the calculated corrosion potential did not match the observed corrosion behavior. Hence, the goal of this study is to get better understanding on Al or Al-Mg alloy coupled to Al-Zn alloy and to provide the calculated corrosion potential representing the corrosion behavior of the ORV material by immersion test, electrochemical tests, and calculation of corrosion and galvanic potential. The corrosion potentials of Al and Al alloys also depended on alloying element as well as surface defects. The corrosion potentials of Al and Al-Mg alloy were changed with time. In the meantime, the corrosion potentials of Al-Zn alloys were not. The corrosion rates of Al-Zn alloys were exponentially increased with zinc contents. The phenomena were explained with the stability of passive film proved by passive current density depending on pH and confirmed by the model proposed by McCafferty. Dissimilar material crevice corrosion (DMCC) test shows that higher content of zinc caused Al-Mg alloy corroded more rapidly, which was due to the fact that higher corrosion rate of Al-Zn makes [$H^+$] and [$Cl^-$] more concentrated within pit solution to corrode Al-Mg alloy. Considering electrochemical reactions within pit as well as bulk in the calculation gives better prediction on the corrosion behavior of Al and Al-Mg alloy as well as the capability of Al-Zn alloy for corrosion protection.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.67-72
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• 1998

Due to excellent corrosion resistance, in particular against sea water, Al-2wt.$\%$Zn alloys have been used as the sacrifice anode material for tube of the ORV. Al-2wt.$\%$Zn alloys thermal-sprayed coating, however, were spalled on the lower part of ORV due to the lack of bonding strength between base material and coating layer and the dropping energy of sea water, To overcome the problems of the thermal spray coating, we developed the cladded tube manufacturing process by coextrusion of the clad and base metal. The corrosion resistance of cladded tube was improved by two times at least, compared with that of the present thermal spray coated vaporizer tubes.

• Journal of the Korean Society of Industry Convergence
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• v.1 no.2
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• pp.49-54
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• 1998

In the catalytic combustor, combustion characteristic and deterioration of catalysts were affected by non-uniformity of pre-mixed gas, Therefore, formation of uniform pre-mixed gas is one of important subjects. In this study, the effect of uniformity and non-uniformity of pre-mixed gas supplied to the catalyst was examined to clarify reaction acceleration and combustion characteristic of the catalytic combustion. It was clarified that static mixer or vaporizer tube length of about 150mm and weak swirl to a combustion air were effictive expedient to make uniform pre-mixed gas. And catalystic inlet temperature needs more than $600^{\circ}C$ with rich pre-mixed gas to active reaction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.161-165
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• 2005

Until now LPG car has drived used to mixer and vaporizer. So LPG car always has problems back fire and when in the winter. LPG Car's Fuel consumption is rather than gasoline. But LPLi Fuel pump located in the fuel tank is directly injection in the engine. So Fuel consumption is better than LPG mixer system and result to reduced exhaust gas. In this paper to reduction of beating noise of LPLi(liquid phase LPG Injection) fuel pump. General speaking we know, beating noise is occur to near frequency each of pump. So we Modification of RPM through chang of amature turn number and area of dimension of the pump's body.

• Journal of ILASS-Korea
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• v.11 no.1
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• pp.30-38
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• 2006

High temperature furnaces such as power plant and incinerator contribute considerable part of NOx generation and face urgent demand of De-NOx system. Reducing agent is injected into the flue gas flow to activate do-NOx system. Almost SCR system adopt vaporized ammonia injection system. Vaporizer, dilution system and additional space are needed to gasify and inject ammonia. Liquid spray injection system can simplify and economize post-treatment system of flue gas. In this study, mixing caused by gas or liquid injection of reducing agent into flue gas duct was investigated experimentally. Carbonated water was used as tracer and simulated agent and mixing of liquid spray in a duct flow was studied. To achieve that, the angle of attack of static mixer is simulated and $CO_2$ concentration is measured.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.595-600
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• 2003

This paper presents the applicability of low caloric synthetic gas from coal gasification to a gas engine system. A commercial LPG engine is modified to use the low caloric synthetic gas from coal gasification as the gas engine fuel. The modification is focused on the fuel supplying system, which includes air flowrate adjusting orifice, gas mixer, vaporizer, preheater, regulators, and fuel tank. The electrical system and others for the alternative fuel are also redesigned and replaced. From the results of engine performance data, we have demonstrated that the engine modified by using coal gasification gas is well operated from idle to wide open throttle conditions although the engine power is somewhat reduced relative to LPG fueled engine. This paper addresses the need to determine the practical potential for such a concept and to identify further research and development efforts that may be necessary.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.210-210
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• 2007

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.116-119
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• 2017

In this paper, natural convection around the ambient evaporator was numerically studied using commercial computational fluid dynamics software. From the simulations, temperature and velocity fields around the evaporator were found as a function of evaporator size and liquefied gas flow rate. The heat transfer coefficient at the external surface of the evaporator was also calculated from the simulation results. In order to give the heat transfer coefficient for various conditions, correlation between Rayleigh number and Nusselt number was proposed.

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.89-89
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• 2005