scholarly journals DEVELOPMENT OF PIN-LEVEL NEUTRONICS/THERMAL-FLUID ANALYSIS COUPLED CODE SYSTEM FOR A BLOCK-TYPE HTGR CORE

2021 ◽  
Vol 247 ◽  
pp. 02041
Author(s):  
Yuk Seungsu ◽  
Tak Nam-il ◽  
Chang Jo Keun
Keyword(s):  
Power Distribution ◽  
Large Change ◽  
Maximum Temperature ◽  
Distribution Data ◽  
Block Type ◽  
High Fidelity ◽  
Code System ◽  
Accurate Analysis ◽  
Fluid Analysis ◽  
Thermal Fluid Analysis

Recently, the coupling between computer codes that simulate different physical phenomena has attracted for more accurate analysis. In the case of high-temperature gas-cooled reactor (HTGR), the coupling between neutronics and thermal-fluid analysis is necessary because of large change of temperature in the reactor core. Korea Atomic Energy Research Institute (KAERI) has developed the coupled code system between a reactor physics analysis code CAPP and a thermal-fluid system safety analysis code GAMMA+ for a block-type HTGR. The CAPP/GAMMA+ coupled code system provides more accurate block-wise distribution data than CAPP or GAMMA+ stand-alone analysis. However, the block-wise distribution data has the limitation in order to predict safety parameters such as the maximum temperature of the nuclear fuel. It is necessary to calculate refined distribution, for example, pin-level (fuel compact level) distribution. In this study, we tried to solve this problem by coupling CAPP and a high-fidelity thermal-fluid analysis code CORONA. CORONA can perform a high-fidelity thermal-fluid analysis of Computational Fluid Dynamics (CFD) level by dividing a block-type HTGR core into small lattices. On the other hand, CAPP can provide a pin power distribution. It is expected that the refined, more accurate distribution data for a block-type HTGR can be obtained by coupling these two codes. This paper presents the development of coupled code system between CAPP and CORONA, and then it is tested on a simple HTGR column problem with encouraging results.

Automatic Thermal Modeling for System Level Design of Electronic Equipment

2003 ◽  
Author(s):  
Kenichiro Aoki ◽  
Koichi Shimizu ◽  
Akira Ueda ◽  
Akira Tamura ◽  
Masanori Motegi
Keyword(s):  
Model Building ◽  
Software Tool ◽  
System Level ◽  
Analysis Model ◽  
Accurate Analysis ◽  
Fluid Analysis ◽  
Analytical Accuracy ◽  
Thermal Fluid Analysis ◽  
Short Time ◽  
Large Investment

The development of hardware needs cost reduction by shortening a development period and reducing experimental man-hour. In order to satisfy these demands, thermal fluid analysis with higher accuracy in short time is indispensable for product development. At present, thermal fluid analyses are conducted using different software tools. Each software tool requires model building and meshing for simulations using its own format. That leads to a large investment in time, and therefore cost. VPS/Simulation-Hub software Fujitsu developed is able to convert data from various CADs. It has the features to create a data fitting to numerical analysis software, create an accurate analysis model, and delete unnecessary components. With these main features, VPS/Simulation-Hub greatly contributes to the man-hour reduction for model building and the improvement of analytical accuracy. In this paper, VPS/Simulation-Hub is introduced with the detail explanation of the above 3 main features.

DYNSUB: A high fidelity coupled code system for the evaluation of local safety parameters – Part I: Development, implementation and verification

2012 ◽  
Vol 48 ◽  
pp. 108-122 ◽  
Author(s):  
Armando Miguel Gomez-Torres ◽  
Victor Hugo Sanchez-Espinoza ◽  
Kostadin Ivanov ◽  
Rafael Macian-Juan
Keyword(s):  
High Fidelity ◽  
Code System ◽  
Safety Parameters ◽  
Local Safety

scholarly journals A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 328 ◽  
Author(s):  
Haonan Tian ◽  
Zhongbao Wei ◽  
Sriram Vaisambhayana ◽  
Madasamy Thevar ◽  
Anshuman Tripathi ◽  
...  
Keyword(s):  
Numerical Model ◽  
Analytical Model ◽  
Electromagnetic Analysis ◽  
Medium Frequency ◽  
Fluid Analysis ◽  
Fluid Behavior ◽  
Proposed Model ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Thermal Fluid Analysis

Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization.

VHTR Core Preliminary Analysis Using NEPHTIS3 / CAST3M Coupled Modelling

2008 ◽  
Author(s):  
Fre´de´ric Damian
Keyword(s):  
Fuel Element ◽  
System Analysis ◽  
Hot Spot ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Design Parameters ◽  
Block Type ◽  
Fuel Temperature ◽  
Coupled Modelling ◽  
The Core

Along with the GFR another gas-cooled reactor identified in the Gen IV technology roadmap, the VHTR is studied in France. Some models have been developed at CEA relying on existing computational tools essentially dedicated to the prismatic block type reactor. These models simulate normal operating conditions and accidental reactor transients by using neutronic [1], thermal-hydraulic, system analysis codes [2], and their coupling [3, 4]. In the framework of the European RAPHAEL project, this paper presents the results of the preliminary investigations carried out on the VHTR design. These studies aimed at understanding the physical aspects of the annular core and to identify the limits of a standard block type VHTR with regard to a degradation of its passive safety features. Analysis was performed considering various geometrical scales: fuel cell and fuel column located at the core hot spot, 2D and 3D core configurations including the coupling between neutronic and thermal-hydraulic. From the thermal analysis performed at the core hot spot, the capability to reduce the maximum fuel temperature by modifying the design parameters such as the fuel compact and the fuel block geometry was assessed. The best performances are obtained for an annular fuel compact geometry with coolant flowing inside and outside the fuel compact (ΔT > 50°C). The reliability of such design option should however be addressed with respect to its performance during the LOFC transient (the residual decay heat will be evacuated by radiation during the transient instead of conduction through graphite). As far as the fuel element geometry is concerned, a gain of approximately 50°C can be achieved by making limited changes on the fuel compact distribution in the prismatic block: reduction of the number of fuel compact in the outer ring of the fuel element where the average ratio between coolant channels and fuel compact is smaller. On the other hand, the adopted modifications should also be evaluated with respect to the maximum temperature gradient achieved in the fuel (amoeba effect). In the end, calculations performed on the full core configuration taking into account the thermal feedback showed that the radial positioning of the fuel elements allows to reduce significantly the power peaking factor and the maximum fuel temperature. The gain on the fuel temperature, which varies during the core irradiation, is in the range 100 – 150°C. Several modifications such as the increase of the bypass fraction and the replacement of a part of the graphite reflector by material with better thermal properties were also addressed in this paper.

Application of Fine Depletion Calculation for LLFPs In-Core Transmutation Evaluation in PWRs

2012 ◽  
Author(s):  
Kun Liu ◽  
Hongchun Wu ◽  
Liangzhi Cao ◽  
Youqi Zheng ◽  
Changhui Wang
Keyword(s):  
Power Distribution ◽  
Critical Concentration ◽  
Verification And Validation ◽  
Code System ◽  
Fuel Management ◽  
Numerical Accuracy ◽  
Analysis And Evaluation ◽  
Evaluation Code ◽  
Flux Calculation ◽  
Numerical Performance

An in-core transmutation analysis and evaluation code, named CATE, considering in-core fine flux calculation and fine depletion process, is verified and validated in the present paper. Verification and Validation of implementations for the OECD/NEA PWR cell benchmark for actinides transmutation, IAEA PWR benchmark and infinite homogenized plate problem to confirm reliability and numerical accuracy for the code have been performed in presented paper. The numerical performance of the code system is demonstrated in the analyses of the in-core fuel management calculation. It is found that the present code system gives stability in prediction of critical concentration of boric solution and radial power distribution. Based on the verifications and validations, a preliminary LLFP transmutation pattern is calculated. Numerical results indicate that CATE can be used not only for the fuel management calculation, but also for in-core transmutation evaluation of PWR.

Optimized Multi-Floor Throughflow Micro Heat Exchangers

2013 ◽  
Author(s):  
Abas Abdoli ◽  
George S. Dulikravich
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Stokes Equations ◽  
Flow Direction ◽  
Computing Time ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Fluid Analysis ◽  
Response Surface Approximations ◽  
Hot Surface

Multi-floor networks of straight-through liquid cooled microchannels have been investigated by performing conjugate heat transfer in a silicon substrate of size 15×15×1 mm. Two-floor and three-floor cooling configurations were analyzed with different numbers of microchannels on each floor, different diameters of the channels, and different clustering among the floors. Thickness of substrate was calculated based on number of floors, diameter of floors and vertical clustering. Direction of microchannels on each floor changes by 90 degrees from the previous floor. Direction of flow in each microchannel is opposite of the flow direction in its neighbor channels. Conjugate heat transfer analysis was performed by developing a software package which uses quasi-1D thermo-fluid analysis and a 3D steady heat conduction analysis. These two solvers are coupled through their common boundaries representing surfaces of the cooling microchannels. Using quasi-1D solver significantly decreases overall computing time and its results are in good agreement with 3D Navier-Stokes equations solver for these types of application. Multi-objective optimization with modeFRONTIER software was performed using response surface approximations and genetic algorithm. Maximizing total amount of heat removed, minimizing coolant pressure drop, minimizing maximum temperature on the hot surface, and minimizing non-uniformity of temperature on the hot surface were four simultaneous objectives of the optimization. Pareto-optimal solutions demonstrate that thermal loads of 800 W cm−2 can be effectively managed with such multi-floor microchannel cooling networks. Two-floor microchannel configuration was also simulated with 1,000 W cm−2 uniform thermal load and shown to be feasible.

INVESTIGATION OF TEMPERATURE RISING MECHANISM IN LONG TUNNEL BY NUMERICAL SIMULATION

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Haeyoung Kim ◽  
Hitoshi Yamada ◽  
Hiroshi Katsuchi ◽  
Soichiro Nakamura
Keyword(s):  
Wind Speed ◽  
Cross Flow ◽  
Initial Condition ◽  
The Past ◽  
Fluid Analysis ◽  
Tunnel Section ◽  
Reduction Effect ◽  
Thermal Fluid Analysis ◽  
Ventilation Fan

Abnormally high temperature inside the long, undergrounded tunnel is a problem in the urban area. As one of the countermeasures, a ventilation fan has been operated. However, the insufficient temperature reduction effect and high cost are an issue and improvement is required. In this study, in order to improve the operating plan of ventilation, the flow field and temperature distribution characteristics are clarified by computational thermal fluid analysis, and the operation of the optimum ventilation was decided. The dominant factors for the temperature rising were identified as traffic volume, lane axis wind speed, cross flow ventilation, and heat flux between tunnel body and air in tunnel. In the analysis, we focused on these four factors, and applied these factors obtained from long-term on-site measurement to the boundary condition and the initial condition. In addition, the amount of heat from vehicle traffic was calculated based on the measurement and the past report results. The analytical model is 1000 m partial tunnel section where the temperature rising was intense. The validation of numerical model was verified from the comparison between the analysis results and the measured values. It was confirmed that the effect of increasing lane axis wind speed as a countermeasure was not significant, and the ventilation amount of crosswind is recommended as 60 m3/s.

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