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후방 캔 압출 공정에서 표면 변형 형태에 대한 펀치 형상의 영향
노정훈(J. H. Noh),김동현(D. H. Kim),황병복(B. B. Hwang) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
This paper is concerned with the analysis on the surface stress profiles of AISI 1015 steel in backward extrusion process. Heavy surface stress such as surface expansion appeared in backward can extrusion process usually leads to very severe tribological conditions along the interface between workpiece and punch land. In the present study, influence on the punch face angle and reduction has been investigated in terms of the surface stress profiles such as surface expansion, pressure exerted on the tool surface between tool and workpiece, respectively. The main goal of this study is to examine the influence of process conditions such as degree of reduction in area and geometries of punch face on the deformation pattern of the model material in backward extrusion, especially for surface stresses. It is well known that among various surface stresses, surface expansion and contact pressure distribution along the die-workpiece interface are closely related to the condition of lubrication at the interface for both solid and liquid lubricants, and contact pressure and sliding distance between workpiece and tool are essential parameters to evaluate the tool wear. The geometrical parameters employed in analysis include the punch face angle of the punch nose as well as reduction ratio. Extensive simulation has been conducted by applying rigid-plastic finite element method to backward can extrusion process under various geometrical conditions. The simulation results are summarized in terms of surface stresses such as surface expansion, pressure and comparison of surface loads for different process conditions, which constitute of surface stress profiles. It was found from the present study that the surface expansion is more influenced by reductions than the punch nose angle.
Numerical Analysis of Integrated Fuel Processing System Considering Thermo-Chemical Energy Balance
노정훈(Noh, Junghun),정혜미(Jung, Hye-Mi),정운호(Jung, Un-Ho),윤왕래(Yoon, Wang-Lai),엄석기(Um, Sukkee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
This paper focuses on a systematic configuration of steam reforming fuel processor, particularly designed for small and medium sized hydrogen production application. In a typical integration of the fuel processor, there exist significant temperature gradients over the entire system which has negative effect on both catalyst life-time and system performance. Also, the volumetric inefficiency should be avoided to obtain the possible compactness for the commercial purpose. In the present work, the computational analysis will be performed to gain the fundamental insight on the transport phenomena and chemical reactions in the reformer consisting of preheating, steam reforming (SR), and water gas shift (WGS) reaction beds in the flow direction. Also, the fuel processing system includes a top-fired burner providing necessary thermal energy for endothermic catalytic reactor. A fully two-dimensional numerical modeling for a integrated fuel processing system is introduced for in-depth analysis of the heat and mass transport phenomena based on surface kinetics and catalytic process. In the model, water gas shift reaction and decomposition reaction were assumed to be at equilibrium. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Finally, the case study was done by considering the key parameters, i.e. steam to carbon (S/C) ratio and temperature. The computer-aided models developed in this study can be greatly utilized for the design of advanced fast-paced compact fuel processors research.
Parametric Study of an Integrated Steam Methane Reformer with Top-Fired Combustor
노정훈(Noh, Jung-Hun),정혜미(Jung, Hye-Mi),김동희(Kim, Donghee),엄석기(Um, Sukkee) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
It is of great importance to predict operating parameter characteristics of an integrated fuel processor by the increased life-time and system performance. In this study, computational analysis is performed to gain fundamental insights on transport phenomena and chemical reactions in reformer which consists of preheating, steam reforming, and water gas shift reaction beds. Also, a top-fired burner locates inside of the reforming system. The combustor is providing thermal energy necessary for the steam reforming bed which is a endothermic catalytic reactor. Two-dimensional numerical model of the integrated fuel processing system is introduced for the analysis of heat and mass transport phenomena as well as surface kinetics and catalytic process. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Subsequently, parameter study using the validated steam methane reforming model was conducted by considering operating parameters, i.e. steam to carbon ratio and temperature.