CFD Preliminary Assessment of the ALFRED FA Thermal-Hydraulics

2020 ◽  
Author(s):  
R. Marinari ◽  
I. Di Piazza ◽  
M. Tarantino ◽  
G. Grasso ◽  
M. Frignani
Keyword(s):  
Temperature Field ◽  
Fuel Assembly ◽  
Mass Flow ◽  
Flow Distribution ◽  
Test Case ◽  
Thermal Hydraulics ◽  
Safety Studies ◽  
Central Interest ◽  
Nominal Condition ◽  
Temperature Constraint

Abstract In the context of GEN-IV heavy liquid metal-cooled reactors safety studies, the coolability of the Fuel Assembly in nominal condition is of central interest. The Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED) is a 300 MWth pool-type reactor aimed at demonstrating the safe deployment of the Generation IV LFR technology. The ALFRED design, currently being developed by the Fostering ALFRED Construction international consortium, is based on prototypical solutions intended to be used in the next generation of lead-cooled Small Modular Reactors. Within the scope of FALCON and in the frame of investigating the thermal-hydraulics of the ALFRED core, a CFD computational model of the general Fuel Assembly (FA) is built looking for the assessment of its thermal field in nominal flow conditions both for the average FA and the hottest one. Starting from the experience in this kind of simulations and in experimental work, the whole model of the ALFRED Fuel Assembly is first presented and calculation of flow and temperature field in nominal conditions is carried out. Results showed that the thermal hydraulic field predicted in the average FA by the code is in good agreement with analytical correlations and the temperature field on the pin clad is acceptable for clad material temperature constraint. About the results on the hot FA test case, the CFD results highlighted a peak temperature on the clad close to the clad temperature constraint. This result led to an upgrade of the mass flow distribution among the FA for achieving a 20% mass flow increase in the hottest one that guarantees higher temperature margin on the clad.

Numerical Simulation on 3D Flow in the Fuel Transfer Canal and Local Flow Field Analysis

2013 ◽  
Author(s):  
Qiang Guo ◽  
Hui Wang
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Fuel Assembly ◽  
Field Analysis ◽  
Thermal Hydraulics ◽  
Spent Fuel ◽  
Complex Flow ◽  
Local Flow ◽  
Fuel Rods ◽  
Safety Research

By application of CFD codes, 3D complex flow field and temperature field in the transfer canal are simulated. It indicates that there is obvious cross-flow in the complex flow path of spent fuel container, and the natural circulation flow brings an inhomogeneous heat-transfer condition to the spent fuel assembly. A model of typical unit of canal is built, and local flow field and temperature field are analyzed with CFD code. The results of thermal hydraulics analysis could be a good reference for nuclear safety research on spent fuel assembly. Considering a conservative operating condition, a case with conservative boundary conditions is investigated by CFD code with 3D model. The result shows that fuel rods in the local region, which are in the container upside and far from holes of wall and roof, get the worst cooling effect, and even maybe boiling occurs in clad surface. Based on the thermal-hydraulics analysis, optimized mechanical designs of container are suggested, the new design would optimize the local flow field, and increase the flow velocity of water, to construct more unhindered convection there, as a result, make spent fuel rods in the bad cooling region get better cooling.

Application of CFD Model for Inlet Flow Region of 17×17 Fuel Assembly

2006 ◽  
Author(s):  
Milorad B. Dzodzo ◽  
Bin Liu ◽  
Pablo R. Rubiolo ◽  
Zeses E. Karoutas ◽  
Michael Y. Young
Keyword(s):  
Fuel Assembly ◽  
Fluid Dynamic ◽  
Flow Distribution ◽  
Flow Region ◽  
Fretting Wear ◽  
Jet Flows ◽  
Cfd Model ◽  
Lateral Velocity ◽  
Fuel Assemblies ◽  
Inlet Conditions

A numerical investigation was performed to study the variation in axial and lateral velocity profiles occurring downstream of the inlet nozzle of a typical Westinghouse 17×17 PWR fuel assembly. A Computational Fluid Dynamic (CFD) model was developed with commercial CFD software. The model comprised the lower region of the fuel assembly, including: the Debris Filter Bottom Nozzle (DFBN), P-grid, Bottom Inconel grid, one and half grid span, as well as the lower core plate hole. The purpose of the study was to obtain insight into the flow redistribution resulting from the interaction of the jet arising from the lower core plate hole and the fuel assembly structure. In particular the axial and lateral velocities before and after the nozzle were studied. The results, axial and lateral velocity contours, streamlines and maximum axial and lateral velocity distributions at various elevations are presented and discussed in relation to the potential risk of high turbulent excitation over the rod and the resulting rod-to-grid fretting-wear damage. The CFD model results indicated that the large jet flows from the lower core plate are effectively dissipated by DFBN nozzle and the grids components of the fuel assembly. The breakup of the large jets in the DFBN and the lower grids helps to reduce the steep velocity gradients and thus the rod vibration and fretting-wear risk in the lower part of the fuel assembly. The presented CFD model is one step towards developing advanced tools that can be used to confirm and evaluate the effect of complex PWR structures on flow distribution. In the future the presented model could be integrated in a larger CFD model involving several fuel assemblies for evaluating the lateral velocities generated due to the non-uniform inlet conditions into the various fuel assemblies.

Numerical Investigation of an Asymmetric Double Suction Centrifugal Compressor With Different Backswept Angle Matching for a Wide Operating Range

2017 ◽  
Author(s):  
Hanzhi Zhang ◽  
Dazhong Lao ◽  
Longyu Wei ◽  
Ce Yang ◽  
Mingxu Qi
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Flow Distribution ◽  
Operating Mode ◽  
Mode Transition ◽  
Distribution Characteristics ◽  
Operating Range ◽  
Stable Operating ◽  
Angle Difference ◽  
Matching Models

The work presented here investigates the characteristics of the different impeller backswept angle matchings for a wide stable operating range in an asymmetric double suction centrifugal compressor. The numerical simulation was employed to investigate the influence of different backswept angle matchings on the stable operating range. The aim is to propose a proper change of the backswept angle matching between two impeller sides to improve the impeller power capability and mass flow distribution, furthermore, to delay the operating mode transition and widen the stable operating range of the compressor. Firstly, the method to determine the optimum backswept angle matching obtained by the theory calculation. Then, three matching models were proposed and analyzed in detail. In three matching models, the backswept angle differences between the front and rear impeller side are 0°, 10° and 20°, respectively. The analysis mainly focused on the influence of the different backswept angle matchings on the compressor flow field characteristics and the mass flow distribution characteristics. The results show that the change of the impeller backswept angle matching can improve the mass flow distribution characteristics for two impeller sides and further reduce the stall mass flow rate of the double suction compressor. The model that the backswept angle difference is 10° can delay the operating mode transition and reduce the stall mass flow of the double suction compressor. The model that the backswept angle difference is 20° can also reduce the stall mass flow and finally enable the front impeller into the stall condition. Therefore, the proper change of the backswept angle matching can achieve the purpose of reducing the stall mass flow and widening the operating range for the double suction centrifugal compressor.

Effects of Inlet Mass Flow Distribution and Magnitude on Reactant Distribution for PEM Fuel Cells

2005 ◽  
Vol 3 (1) ◽  
pp. 45-50 ◽  
Author(s):  
M. McGarry ◽  
L. Grega
Keyword(s):  
Fuel Cell ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Separation ◽  
Flow Distribution ◽  
Pem Fuel Cells ◽  
Local Flow ◽  
Flow Rates ◽  
Large Active Area ◽  
Mass Flow Rates

The mass flow distribution and local flow structures that lead to areas of reactant starvation are explored for a small power large active area PEM fuel cell. A numerical model was created to examine the flow distribution for three different inlet profiles; blunt, partially developed, and fully developed. The different inlet profiles represent the various distances between the blower and the inlet to the fuel cell and the state of flow development. The partially and fully developed inlet profiles were found to have the largest percentage of cells that are deficient, 20% at a flow rate of 6.05 g/s. Three different inlet mass flow rates (stoichs) were also examined for each inlet profile. The largest percent of cells deficient in reactants is 27% and occurs at the highest flow rate of 9.1 g/s (3 stoichs) for the partially and fully developed turbulent profiles. In addition to the uneven flow distribution, flow separation occurs in the front four channels for the blunt inlet profile at all flow rates examined. These areas of flow separation lead to localized reactant deficient areas within a channel.

scholarly journals MODEL OF HEAT SIMULATOR FOR DATA CENTERS

2016 ◽  
Vol 56 (4) ◽  
pp. 301-305
Author(s):  
Jan Novotný ◽  
Jiří Nožička
Keyword(s):  
Temperature Field ◽  
Heat Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Data Centers ◽  
Heat Output ◽  
Heat Flow Rate ◽  
Flow Rates ◽  
Piv Method ◽  
Mass Flow Rates

The aim of this paper is to present a design and a development of a heat simulator, which will be used for a flow research in data centers. The designed heat simulator is based on an ideological basis of four-processor 1U Supermicro server. The designed heat simulator enables to control the flow and heat output within the range of 10–100 %. The paper covers also the results of testing measurements of mass flow rates and heat flow rates in the simulator. The flow field at the outlet of the server was measured by the stereo PIV method. The heat flow rate was determined, based on measuring the temperature field at the inlet and outlet of the simulator and known mass flow rate.

CFD-Tool for Thermal-Hydraulics Pressurised Thermal Shock Analysis: Qualification of the Code_Saturne

2002 ◽  
Author(s):  
A. Martin ◽  
S. Bellet
Keyword(s):  
Thermal Shock ◽  
Cold Water ◽  
Life Time ◽  
Test Case ◽  
Fluid Temperature ◽  
Thermal Hydraulics ◽  
Numerical Tools ◽  
Physical Phenomena ◽  
Numerical Program ◽  
Reactor Pressure

This paper explains the numerical program concerning the new thermalhydraulic Code_Saturne qualification for Safety Injection studies. Within the frame of the plant life time project, an analysis has shown that the most severe loading conditions are generated by a pressurised injection of cold water in the downcomer of a Reactor Pressure Vessel. For this kind of transients, a thermal hydraulics study has to be carried out in order to better adjust the accurate distribution of the fluid temperature in the downcomer. For that, the numerical tools have to be able to simulate the physical phenomena present during the Pressurised Thermal Shock. (PTS). For this qualification task, we have investigated one configuration related to an injection of cold water particularly in cold leg but also in a downcomer. One experiment test case has been studied and this paper gives a comparison between experiment and numerical results in terms of temperature field.

Numerical Analysis of the Flow and Heat Transfer in the Sub-Channel of Supercritical Water Reactor

2013 ◽  
Author(s):  
Ajoy Debbarma ◽  
K. M. Pandey
Keyword(s):  
Heat Transfer ◽  
Fuel Assembly ◽  
Supercritical Water ◽  
High Performance ◽  
Flow Distribution ◽  
Diameter Ratio ◽  
Light Water Reactor ◽  
Water Reactor ◽  
Fuel Rod ◽  
Gap Width

Research activities are ongoing for High performance light water reactor (HPLWR) with square double rows fuel assembly to develop nuclear power plants with the purpose to achieve a high thermal efficiency and to improve their economical competitiveness. However, there is still a big deficiency in understanding and prediction of heat transfer in supercritical fluids. This paper evaluates three-dimensional turbulent flow and convective heat transfer in a single-phase and steady-state sub-channel of HPLWR by using general computational fluid dynamics code, Ansys 14 Fluent. The major concern using supercritical water as work fluid is the heat transfer characteristics due to large variations of thermal properties of supercritical water near pseudo-critical line. In order to ensure the safety of operation in High performance light water reactor (HPLWR), heat transfer deterioration (HTD) must be avoided. Numerical results prove that the RNG k-e model with the enhanced near-wall treatment obtained the most satisfactory prediction and lead to satisfactory simulation results. The HPLWR Square fuel assembly has many square-shaped water rods, Out of four types of sub-channels; three sub-channels SC-1, SC-2 and SC-3 are investigated (adjacent to the side of the moderator flow channels (SC-1) (moderator tube and assembly gap), central sub-channels formed by four fuel rods (SC-2), adjacent to the corner of the moderator tube (SC-3). Since coolant flow distribution in the fuel assembly strongly depends on the gap width between the fuel rod and water rod, fuel rod pitch to diameter ratio 1.1–1.4 with 8mm diameter are considered for simulation. Sub-channel analysis clarifies that coolant flow distribution becomes uniform when the gap width is set to 1.0 mm. was less than 620°C. Effects of various parameters, such as boundary conditions and pitch-to-diameter ratios, on the mixing phenomenon in sub-channels and heat transfer are investigated. The effect of pitch-to-diameter ratio (P/D) on the distributions of surface temperature and heat transfer coefficient (HTC) in a sub-channel, it was found that HTC increases with P/D 1.1 first and then decreases with increasing P/D ratio. Apart from the basic geometry sub-channel, a square sub-channel with a wire-wrapped rod inside has been chosen to investigate the “wire effect”.

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