scholarly journals Heat Transfer Calculation on Plate-Type Fuel Assembly of High Flux Research Reactor

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Daxin Gong ◽  
Shanfang Huang ◽  
Guanbo Wang ◽  
Kan Wang
Keyword(s):  
Heat Transfer ◽  
Fuel Assembly ◽  
Research Reactor ◽  
Hot Spot ◽  
Saturation Temperature ◽  
High Flux ◽  
Turbulence Flow ◽  
Commercial Code ◽  
Fuel Assemblies ◽  
And Control

Heat transfer characteristics of fuel assemblies for a high flux research reactor with a neutron trap are numerically investigated in this study. Single-phase turbulence flow is calculated by a commercial code, FLUENT, where the computational objective covers standard and control fuel assemblies. The simulation is carried out with an inlet coolant velocity varying from 4.5 m/s to 7.5 m/s in hot assemblies. The results indicate that the cladding temperature is always lower than the saturation temperature in the calculated ranges. The temperature rise in the control fuel assembly is smaller than that of the standard fuel assembly. Additionally, the assembly with a hot spot is specially studied, and the safety of the research reactor is also approved.

Embedded Two-Phase Cooling of High Flux Electronics via Micro-Enabled Surfaces and Fluid Delivery Systems (FEEDS)

2015 ◽  
Author(s):  
Raphael Mandel ◽  
Serguei Dessiatoun ◽  
Patrick McCluskey ◽  
Michael Ohadi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Saturation Temperature ◽  
Absolute Pressure ◽  
High Flux ◽  
Vapor Quality ◽  
Two Phase ◽  
Fluid Delivery ◽  
Future Work

This work presents the experimental design and testing of a two-phase, embedded manifold-microchannel cooler for cooling of high flux electronics. The ultimate goal of this work is to achieve 0.025 cm2-K/W thermal resistance at 1 kW/cm2 heat flux and evaporator exit vapor qualities at or exceeding 90% at less than 10% absolute pressure drop. While the ultimate goal is to obtain a working two-phase embedded cooler, the system was first tested in single-phase mode to validate system performance via comparison of experimentally measured heat transfer coefficient and pressure drop to the values predicted by CFD simulations. Upon validation, the system was tested in two phase mode using R245fa at 30°C saturation temperature and achieved in excess of 1 kW/cm2 heat flux at 45% vapor quality. Future work will focus on increasing the exit vapor quality as well as use of SiC for the heat transfer surface upon completion of current experiments with Si.

scholarly journals Numerical Investigation of Conjugated Heat Transfer of the Plate-Type Fuel Assembly in the Research Reactor

2021 ◽  
Vol 9 ◽  
Author(s):  
Quan Li ◽  
Qiang Ma ◽  
Yuanming Li ◽  
Ping Chen ◽  
Chao Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fuel Assembly ◽  
Power Density ◽  
Research Reactor ◽  
Flow Boiling ◽  
Fluid Velocity ◽  
Rensselaer Polytechnic Institute ◽  
Conjugated Heat Transfer ◽  
Type Fuel ◽  
Plate Type

In nuclear reactors, the research of conjugated heat transfer between the fuel and coolant in the fuel assembly is fundamental for improving the safety, reliability and economy. The numerical approach based on Computational Fluid Dynamics (CFD) can be used to realize the rapid analysis of the conjugated heat transfer. Besides, the numerical simulation can provide detailed physical fields that are useful for the designing and optimizing of the fuel assembly. The plate-type fuels are generally used to enhance heat transfer in research reactors with high power density. In this study, a standard plate-type fuel assembly in the research reactor was taken into consideration. The solid-fluid conjugated heat transfer of the fuel assembly and coolant was numerically investigated. In the fluid region, the subcooled flow boiling simulation model was established by implementing the Rensselaer Polytechnic Institute model into the Euler multi-phase flow method. The results show that the conjugated heat transfer of the fuel assembly and coolant can be simulated using the model established in this work. The influence of fluid velocity, power density and the width of the flow channel on the temperature distribution and the conjugated heat transfer was investigated and discussed.

Study on Pool Boiling Behavior of the Spent Fuel Under Accident Conditions

2017 ◽  
Author(s):  
Shang Gao ◽  
Daogang Lu ◽  
Han Wang ◽  
Yuhang Zhong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Temperature ◽  
Fuel Assembly ◽  
Saturation Temperature ◽  
Spent Fuel ◽  
Decay Heat ◽  
Phase Calculation ◽  
Spent Fuel Pool

Under normal refueling and emergency full-core offload condition, the fuel assembly is removed to the Spent Fuel Pool (SFP). Decay heat produced by the spent fuel is carried out by the cooling system. Active cooling method is adopted by the traditional PWR nuclear power plants, which means decay heat is taken away depending on forced circulation of the pump. However, the spent fuel pool, under accident condition, will lost the forced circulating cooling capacity, which will be a threat of for the fuel building safety. To study the thermal-hydraulic characteristics in the SFP missing the forced cooling, through CFX methodology and experiment, change of temperature and heat transfer coefficient of the wall of the heating tube at different heights were discussed, meanwhile the streamline chart and temperature contour were obtained as well. The present result indicated that under different power conditions, different height of water temperature increased at first and then trend to stable at saturation temperature. For a single 9*9 spent fuel assembly, water temperature at the higher height is higher than the lower at the same time, and water temperature at higher location reached a stable value more quickly. In addition, power value had a significant impact on the time of reaching saturation temperature, for example, 7000s is needed to reach saturation under 8.68KW condition while only 3000s under 16.12KW, which illustrates that fuel unload power is crucial to the SFP safety. Based on the experiment data and single phase calculation, heat transfer coefficient at different height of the heating tube decreased slowly at first, and then increased. Especially, heat transfer coefficient at the highest test point rapidly decreased at one point because of boiling crisis.

Lime salts: origin and control in beet processing

2020 ◽  
pp. 282-287
Author(s):  
Jan Maarten de Bruijn
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Performance Indicator ◽  
Key Performance Indicator ◽  
Process Measures ◽  
Trouble Shooting ◽  
Important Chemical ◽  
And Control ◽  
Affect Processing ◽  
White Sugar

Lime salts in the thin juice obtained after juice purification is one of the most important chemical KPI’s (Key Performance Indicator) in beet processing. Too high lime salts content will significantly affect processing costs – particularly energy – due to scaling of heat exchange surfaces thus decreasing heat transfer. In addition, high lime salts are at the origin of turbidity and insoluble solids in white sugar. Therefore, it is of the utmost importance to understand the chemistry behind lime salts in beet processing in order to be able preventing too high lime salts contents in thin juice. This paper will explain the details of the chemistry behind the presence of lime salts. Further, a trouble-shooting guide is included to elucidate the different causes for high lime salts contents and how these causes can be identified, as well as the process measures to reduce the lime salts content in thin juice.

scholarly journals Analysis of the Accelerator-Driven System Fuel Assembly during the Steam Generator Tube Rupture Accident

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1818
Author(s):  
Di-Si Wang ◽  
Bo Liu ◽  
Sheng Yang ◽  
Bin Xi ◽  
Long Gu ◽  
...  
Keyword(s):  
Fuel Assembly ◽  
Steam Generator ◽  
Metal Flow ◽  
Maximum Temperature ◽  
Steam Generator Tube ◽  
Driven System ◽  
Fuel Assemblies ◽  
Accelerator Driven System ◽  
The Impact ◽  
Steam Bubble

China is developing an ADS (Accelerator-Driven System) research device named the China initiative accelerator-driven system (CiADS). When performing a safety analysis of this new proposed design, the core behavior during the steam generator tube rupture (SGTR) accident has to be investigated. The purpose of our research in this paper is to investigate the impact from different heating conditions and inlet steam contents on steam bubble and coolant temperature distributions in ADS fuel assemblies during a postulated SGTR accident by performing necessary computational fluid dynamics (CFD) simulations. In this research, the open source CFD calculation software OpenFOAM, together with the two-phase VOF (Volume of Fluid) model were used to simulate the steam bubble behavior in heavy liquid metal flow. The model was validated with experimental results published in the open literature. Based on our simulation results, it can be noticed that steam bubbles will accumulate at the periphery region of fuel assemblies, and the maximum temperature in fuel assembly will not overwhelm its working limit during the postulated SGTR accident when the steam content at assembly inlet is less than 15%.

scholarly journals Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

Comparison of a Conventional Thermal Analysis of a Turbine Cascade to a Full Conjugate Heat Transfer Computation

2008 ◽  
Author(s):  
Christoph Starke ◽  
Erik Janke ◽  
Toma´sˇ Hofer ◽  
Davide Lengani
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Conjugate Heat Transfer ◽  
Complex Geometry ◽  
Thermal Analyses ◽  
Turbine Cascade ◽  
Transfer Coefficients ◽  
Commercial Code ◽  
Blade Tip ◽  
Transfer Method

Recent development in commercial CFD codes offers possibilities to include the solid body in order to perform conjugate heat transfer computations for complex geometries. The current paper aims to analyse the differences between a conjugate heat transfer computation and conventional uncoupled approaches where a heat transfer coefficient is first derived from a flow solution and then taken as boundary condition for a thermal conduction analysis of the solid part. Whereas the thermal analyses are done with a Rolls-Royce in-house finite element code, the CFD as well as the conjugate heat transfer computation are done using the new version 8 of the commercial code Fine Turbo from Numeca International. The analysed geometry is a turbine cascade that was tested by VKI in Brussels within the European FP6 project AITEB 2. First, the paper presents the aerodynamic results. The pure flow solutions are validated against pressure measurements of the cascade test. Then, the heat transfer from flow computations with wall temperature boundary conditions is compared to the measured heat transfer. Once validated, the heat transfer coefficients are used as boundary condition for three uncoupled thermal analyses of the blade to predict its surface temperatures in a steady state. The results are then compared to a conjugate heat transfer method. Therefore, a mesh of the solid blade was added to the validated flow computation. The paper will present and compare the results of conventional uncoupled thermal analyses with different strategies for the wall boundary condition to results of a conjugate heat transfer computation. As it turns out, the global results are similar but especially the over-tip region with its complex geometry and flow structure and where effective cooling is crucial shows remarkable differences because the conjugate heat transfer solution predicts lower blade tip temperatures. This will be explained by the missing coupling between the fluid and the solid domain.

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