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1 - 3:00 - Seung Jun , Arvind Atreya
Radiative Homogeneous Combustion and Its Application to High Temperature Furnaces
Abstract:
The objective of this research is to develop and conduct a full-scale demonstration of new furnace combustion technology to significantly improve energy efficiency, reduce cost and reduce pollutant formation in the steel reheating process. The new Radiative Homogeneous Combustion (RHC) technology to be optimized and demonstrated is inexpensive, easy to implement and has been extensively tested in a small-scale laboratory furnace. This paper presents an experimental and numerical investigation of the Radiative Homogeneous Combustion (RHC) technology. The experimental results are compared with predictions using the Fire Dynamics Simulator (FDS) developed by National Institute of Standards and Technology (NIST). The numerical results were found to be in good agreement with the experimental data. |
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2 - 3:15 - Hongjong Jin
Numerical Simulation of the Liquid Flow in the Lower Part of the Blast Furnace
Abstract:
High permeability of the gas and molten materials in the dropping zone of a blast furnace is the major factor for achieving stable furnace operation with high productivity. Basic studies of the flow behavior of liquids in a packed bed are required to grasp the effect of various operational changes on conditions in the dropping zone. At first the simple geometry is used for the analysis of the liquid flow before the real geometry is used. And the commercial code is simulated after the governing equation is derived for each phase. Continuous flow is assumed for each phase in the derivation of the equation of motion and a generalized mathematical model for the flow of four fluids will be proposed for obtaining the numerical solution. In this research gas and liquid are considered for the mathematical formulation. The solid phase is fixed and has constant porosity. The interactions between gas and liquid is derived by the porosity which means volume ratio of each phase. |
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3 - 3:30 - Seunghwan Keum , Dennis Assanis
Modified flamelet equation for direct injection application
Abstract:
The flamelet equations have been widely used in non-premixed turbulent combustion modeling. However, spray and evaporation has not been considered throughly in previous approaches. The flamelet equations are modified to include the effect of direct injection in this research. Following equations have additional source terms which represent the effect of evaporation. An operator splitting scheme was applied for source term treatment. Preliminary results on the modified flamelet model will be presented. |
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4 - 3:45 - Brian Elbing , Steven L. Ceccio
Effect of Surface Roughness on Polymer Drag Reduction within a High-Reynolds-Number Turbulent Boundary Layer
Abstract:
An experiment conducted at the U.S. Navy's LCC investigated the effect of wall roughness polymer drag reduction (PDR) within a high-Reynolds-number turbulent boundary layer. Testing was performed in two parts: 1) PDR experiment on a 12.9 m long, 3.05 m wide hydro-dynamically smooth flat plate and 2) PDR experiment on the same model with the entire model roughened. The roughness was produced by blowing glass beads into epoxy paint that coated the surface. The roughened model had an average roughness height ranging between 307 and 1154 μm. Drag reduction was determined using six, stream-wise located integrated skin-friction balances. Flow sampling was also made at three stream-wise located ports. The sampling ports were used to determine the amount of polymer degradation, if any, caused by the turbulent flow. Both the skin-friction measurements and sampling analysis indicates that wall roughness in a turbulent boundary layer significantly increases degradation of polymer solutions. |
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4:00 - Break |
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5 - 4:15 - Jongseop Lee , Do Hyung Choi
Decay Rate of Leakage Flow for Two Network Systems of Complex Geometry
Abstract:
Analytical and numerical solutions for network flow model with corrugated membrane are presented. Two separate network systems of complex geometry, in which each system is maintained at a constant pressure, are connected through a leakage pipe. When the blocked leakage pipe is opened suddenly, the different pressure level creates flow from one system to the other until the equilibrium pressure is reached. The decay rate of the flow is solved directly by the Laplace transform and the normal mode analysis. Using the normal mode analysis, the decay rate is estimated by enforcing that the determinant be zero for the system to have a nontrivial solution. The decay rate is also derived analytically from perturbation expansion. The analytical solution of network flow enables us to easily estimate the decay rate. The analytic and the numerical solutions are in good agreement, and the analytic decay time compares favorably with the measured data. |
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6 - 4:30 - Jisung Lee
Experimental Investigation on the Cryogenic Thermosiphon Using N2 and CF4 Mixture as the Working Fluid
Abstract:
A thermosiphon is utilized as a thermal shunt to reduce the cool-down time of a cryogenic system cooled by a two stage coyocooler. The cool-down time reduction by the thermosiphon is determined by the type of working fluid which is directly related to the operating temperature of the thermosiphon. A mixed working fluid has a potential to widen the operation temperature range of the thermosipohon. In this study, the thermosiphon using nitrogen and CF4 mixture as the working fluid is fabricated and tested to verify its transient heat transfer performance. The thermosiphon with the mixed working fluid has no noticeable reduction of cool-down time compared with that of the thermosiphon with pure working fluid in this experiment. However, it seems that the thermosiphon with mixed working fluid may have an advantage according to the cooling capacity of a cryocooler and the size of a cooling object.
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7 - 4:45 - Chung-Yin Tsai , Hong G. Im
A Computational Model for Pyrolysis, Gasification and Heat Transfer in a RDF Fixed-Bed Gasifier
Abstract:
To develop a predictive modeling capability for municipal waste gasification process, a 3-dimensional simulation code is developed based on the SIMPLE algorithm with momentum interpolation for pressure-correction. The two-phase flow and heat transfer processes due to the solid waste stack is modeled by a single-equation porous medium formulation with Darcy approximation. The pyrolysis process is described by a nonlinear Eulerian pyrolysis model to determine the porosity profile as well as the corresponding pyrolysis rate of the waste material. This generalized method simplifies the multiphase governing equations into gas phase equations. Polymethyl methacrylate (PMMA) was used as a test waste material for the simulation. Combustion behavior corresponding to the waste porosity, inlet conditions is studied for a range of operating conditions. |
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8 - 5:00 - Won Chan Park , Arvind Atreya
Determination of Pyrolysis Temperature for Infinite Rate Kinetics Models of Charring Materials
Abstract:
An energy and mass balanced method to determine the pyrolysis temperature for infinite rate kinetics models is proposed. The concept of the proposed method is to find the pyrolysis temperature that consumes the same amount of energy to produce the same amount of mass when using the pyrolysis temperature (infinite rate kinetics) model as when using the finite rate kinetics model for the entire charring process. The resulting pyrolysis temperature has the form of pyrolysis rate weighted average temperature. Comparison between finite rate and infinite rate models for various boundary conditions, geometries, heats of decomposition, kinetic parameters and assumptions used in the literature were studied to assess the proposed method. For practical application, the model predictions are compared with experimental measurements of wood cylinder pyrolysis. |
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1 - Jim Lewis , Steve Wright
Geysers in Rapidly Filling Stormwater Storage Tunnels
Abstract:
The rapid filling of a stormwater storage tunnel is accompanied by a flow regime transition from free surface to pressurized flow. This unsteady process can result in air pockets being trapped and pressurized in the system. As these air pockets reach a ventilation shaft, they can be quickly released upward in an air-water mixture. This process potentially results in the untreated wastewater returning to the surface. Laboratory experiments were used to observe the formation of pressurized air pockets and geysering events. The researchers show that the geysering phenomenon can be significantly reduced by adjusting the geometry of the ventilation shafts. |
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2 - Jisung Lee
Experimental Investigation on the Cryogenic Thermosiphon Using N2 and CF4 Mixture as the Working Fluid
Abstract:
A thermosiphon is utilized as a thermal shunt to reduce the cool-down time of a cryogenic system cooled by a two stage coyocooler. The cool-down time reduction by the thermosiphon is determined by the type of working fluid which is directly related to the operating temperature of the thermosiphon. A mixed working fluid has a potential to widen the operation temperature range of the thermosipohon. In this study, the thermosiphon using nitrogen and CF4 mixture as the working fluid is fabricated and tested to verify its transient heat transfer performance. The thermosiphon with the mixed working fluid has no noticeable reduction of cool-down time compared with that of the thermosiphon with pure working fluid in this experiment. However, it seems that the thermosiphon with mixed working fluid may have an advantage according to the cooling capacity of a cryocooler and the size of a cooling object. |
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3 - Hongjong Jin
Numerical Simulation of the Liquid Flow in the Lower Part of the Blast Furnace
Abstract:
High permeability of the gas and molten materials in the dropping zone of a blast furnace is the major factor for achieving stable furnace operation with high productivity. Basic studies of the flow behavior of liquids in a packed bed are required to grasp the effect of various operational changes on conditions in the dropping zone. At first the simple geometry is used for the analysis of the liquid flow before the real geometry is used. And the commercial code is simulated after the governing equation is derived for each phase. Continuous flow is assumed for each phase in the derivation of the equation of motion and a generalized mathematical model for the flow of four fluids will be proposed for obtaining the numerical solution. In this research gas and liquid are considered for the mathematical formulation. The solid phase is fixed and has constant porosity. The interactions between gas and liquid is derived by the porosity which means volume ratio of each phase. |
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4 - SeungHwan Keum , Dennis N. Assanis
Modified Flamelet Equation for Direct Injection Application
Abstract:
The flamelet equations have been widely used in non-premixed turbulent combustion modeling. However, spray and evaporation has not been considered throughly in previous approaches. The flamelet equations are modified to include the effect of direct injection in this research. Following equations have additional source terms which represent the effect of evaporation. An operator splitting scheme was applied for source term treatment. Preliminary results on the modified flamelet model will be presented. |
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5 - Jongseop Lee , Do Hyung Choi
Decay Rate of Leakage Flow for Two Network Systems of Complex Geometry
Abstract:
Analytical and numerical solutions for network flow model with corrugated membrane are presented. Two separate network systems of complex geometry, in which each system is maintained at a constant pressure, are connected through a leakage pipe. When the blocked leakage pipe is opened suddenly, the different pressure level creates flow from one system to the other until the equilibrium pressure is reached. The decay rate of the flow is solved directly by the Laplace transform and the normal mode analysis. Using the normal mode analysis, the decay rate is estimated by enforcing that the determinant be zero for the system to have a nontrivial solution. The decay rate is also derived analytically from perturbation expansion. The analytical solution of network flow enables us to easily estimate the decay rate. The analytic and the numerical solutions are in good agreement, and the analytic decay time compares favorably with the measured data. |
