Clinical Characteristics of Radiation Oncology in Korea during Past 10 Years

To understand trends in the clinical characteristics of radiation oncology over the last 10 yr in Korea, annual survey questionnaires were sent to all of Korean radiation oncology facilities since 1990. Questionnaires addressed basic radiation therapy facilities and the clinical information. Responses were obtained from all facilities, and data collected from 1997 to 2006 was analyzed. The numbers of new patients that have undergone radiation therapy and the numbers of hospitals with a department of radiation oncology have steadily increased over the past 10 yr, and totaled 37,215 patients and 60 hospitals, respectively, in 2006. However, the proportion of patients irradiated among total cancer patients has remained below 30% over the last 10 yr. The numbers of prostate cancer, breast cancer, and hepatoma have increased by more than 3 fold over the past 10 yr. Moreover, the percentage of irradiated patients treated by brachytherapy was 10.3% in 1997, but this gradually fell to only 4.2% in 2006. The information collected described the role played by radiation oncology in Korea. Continuous surveys are required to enable trends to be detected

THERMIT sodium version, Simulation of sodium boiling experiments with.

Natural and forced convection experiments(SBTF and French) are simulated with the sodium version of the thermal-hydraulic computer code THERMIT. Simulation is done for the test secti- -on with the pressure-velocity boundary condition and subsequ- -ently extended to the whole loop. For the test section simu- -lation, a s.teady-state and transient calculations are perform- -ed and compared with experimental data. For the loop simula- -tion, two methods are used, a simulated 1-D loop and an actual 1-D loop. In the simulated 1-D loop analysis, the vapor densi- -ty is increased by one hundred and two hundred times to avoid the code failure and the results still showed some of the impor- -tant characteristics of the two-phase flow oscillation in a loop. A mathematical model is suggested for the two-phase flow oscillation. In the actual 1-D loop, only the single phase calculation was performed and turned out to be nearly the same as the simulated 1-D loop single phase results.In the process of simulation, it is discovered that the energy conservation equations of THERMIT fails to conserve energy by a small amount due to interfacial mass transfer and frictional dissipation of mechanical into thermal energy. The problems and applicability of the THERMIT physical models are also discussed

Computational Analysis of Thermoacoustic Instabilities in an Industrial Oil Furnace

1

Fluid dynamic simulations, Treatment of physical and numerical diffusion in.

A computer code is developed to predict the behavior of the hydrogen gas in the containment aftet a loss-ofcoolant accident. The conservation equations for the four components, i.e., air, hydrogen, steam and water, are set up and solved numerically by decoupling the continuity and momentum equations from the energy, mass diffusion and turbulence equations. The homogeneous mixture form is used for the momentum and energy equations and the steam and liquid droplets are assumed to be in the saturation state.There are two diffusion processes, molecular and turbulent, which should be modelled in different ways. Molecular diffusion is modelled by Wilke's formula for the multi-component gas diffusion, where the diffusion constants are dependent on the relative concentrations. Turbulent diffusion is basically modelled by the k- model with modifications for low Reynolds number flow effects. Numerical diffusion is eliminated by a corrective scheme which is based on accurate prediction of cross-flow diffusion. The corrective scheme in a fully explicit treatment is both conservative and stable, therefore can be used in long transient calculations. The corrective scheme allows relatively large mesh sizes without introducing the false diffusion and the time step size of the same order of magnitude as the Courant limit may be used.Sponsored by Boston Edison Co., Duke Power Co., Northeast Utilities Service Corp., and Public Service Electric and Gas Co. of New Jersey

CFD Simulation of CO Emission from a Heat Recovery Steam Generator

1

Numerical Study of Combustion Characteristics for Hydrogen Content in Syngas in Opposed-Flow Flame

Various researches are being conducted to reduce greenhouse gases generated by the consumption of traditional energy resources. This study was conducted to numerically analyze the combustion characteristics and N-S reaction behavior with respect to the H2 content of syngas composed of CO and H2 in pressurized air combustion. A non-premixed opposed flow flame model was applied a modified detailed mechanism with S-chemistry was developed based on GRI 3.0 to simulate the syngas reaction. As the hydrogen content increased, the flame thickness increased due to the fast reactivity of hydrogen. In the rich region, NO and SO2 were reduced by reaction with H radical and H bonding of NO was suppressed by the formation of HOSO.22Nkc

Numerical Analysis of Chemical Characteristics of Homogeneous CO/H2/NO in Pressurized Oxy-Fuel Combustion

This study was performed by the numerical approach to investigate chemical behaviors of homogeneous syngas (CO/H2) with nitric monoxide (NO) in pressurized oxy-fuel conditions. Hydrogen had a dominant effect to the ignition delay time of syngas due to the fast chemistry of its oxidation. Combustion was promoted by NO at the low temperature region. It was by the additional heat release through NO oxidation and production and consumption of major radicals related to the ignition. Two stage ignition behavior was shown in the pressurized condition by the accumulation of H2O2 produced from HO2 radical. Additional NO oxidation was induced by the pressurized oxy-fuel condition to produce NO2.22Nkc

Analysis of mean orientation vector and mean curvature in statistically steady turbulent premixed combustion

1

Model order reduction by proper orthogonal decomposition for a 500 MWe tangentially fired pulverized coal boiler

Reduced order models (ROMs) are constructed by proper orthogonal decomposition (POD) and regression by Kriging and Radial Basis Neural Network (RBFN) for a 500 MWe tangentially fired pulverized coal boiler. POD is performed to extract low-dimensional basis vectors to reproduce 3-D distribution of reacting scalars with respect to the operation parameters of total secondary air (TSA) and burner zone stoichiometric ratio (BSR). The ROMs by Kriging and RBFN both reproduce the scalar fields within 6% averaged relative L2 norm error at three validation points in the parameter space. It is possible to reproduce a 3-D scalar field at any unexplored operation condition within a few seconds through parallel computation of the ROM. It allows fast evaluation of the effects of varying operation parameters in the design stage and real time response of a digital twin based on the ROM for smart operation and maintenance of industrial combustion facilities. ? 202111Nsciescopu

Simulation of Flow field and Carbon Monoxide Emission in an Industrial Scale Heat Recovery Steam Generator

Computational simulation is performed for flow field and carbon monoxide (CO) emission in an industrial scale heat recovery steam generator (HRSG) by ANSYS Fluent v13. The geometrical details are reproduced with burner holes and swirler blades simplified to avoid excessive computational burden. Turbulence-chemistry interaction is modeled by the steady laminar flamelet model (SLFM) and the unsteady laminar flamelet model (ULFM) through a lookup table without time consuming integration of stiff elementary reaction steps. The ULFM showed good agreement with measured CO mass fractions near the extinction limit for Sandia Flame D in Turbulent Nonpremixed Flame (TNF) Workshop. The proper trends of variation and the same order of magnitude of CO mass fractions were reproduced by the ULFM for the three reference cases of varying HRSG loads. Parametric investigations were performed to identify the factors influencing exhaust CO with respect to the number and layout of activated burners and flow correction device (FCD). Results showed two competing factors for CO emission, rich mixture by undermixing and lean mixture by overmixing, which may lead to local extinction below the flammability limit.11sciescopu