• Title/Summary/Keyword: Fuel bundle

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Heat Transfer Characteristics of Tube Bundle Type Beat Exchanger for LFG and LNG Mixed Fuel (LFG와 LNG 혼합연료의 조성에 따른 다관형 열교환기에서의 열전달 특성)

  • Jeon Yong-Han;Kim Yong;Seo Tae-Beom
    • Journal of Energy Engineering
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    • v.15 no.1 s.45
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    • pp.45-51
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    • 2006

  • The purpose of this study is to investigate experimentally the heat transfer characteristics of combustion gas or a mixture fuel of LFG and LNG as compared LFG, LNG A Pilot combustion system is constructed. Tube bundle type heat exchangers with vertical and horizontal baffles are used, and the experiment is carried out for different operating conditions, the heating value, the concentration of methane (44.5%, 54.5%). The results show that the Nusselt number of LNG is higher than that of LFG at the same Reynolds number, and in case LFG, the Nusselt number of the mixture of LFG and LNG is larger than that of LFG alone. Therefore, heat transfer is improved by using LFG that is added to LNG pertinently, if and instability of LFG supply will be relaxed.

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Application of POD reduced-order algorithm on data-driven modeling of rod bundle

  • Kang, Huilun;Tian, Zhaofei;Chen, Guangliang;Li, Lei;Wang, Tianyu
    • Nuclear Engineering and Technology
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    • v.54 no.1
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    • pp.36-48
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    • 2022

  • As a valid numerical method to obtain a high-resolution result of a flow field, computational fluid dynamics (CFD) have been widely used to study coolant flow and heat transfer characteristics in fuel rod bundles. However, the time-consuming, iterative calculation of Navier-Stokes equations makes CFD unsuitable for the scenarios that require efficient simulation such as sensitivity analysis and uncertainty quantification. To solve this problem, a reduced-order model (ROM) based on proper orthogonal decomposition (POD) and machine learning (ML) is proposed to simulate the flow field efficiently. Firstly, a validated CFD model to output the flow field data set of the rod bundle is established. Secondly, based on the POD method, the modes and corresponding coefficients of the flow field were extracted. Then, an deep feed-forward neural network, due to its efficiency in approximating arbitrary functions and its ability to handle high-dimensional and strong nonlinear problems, is selected to build a model that maps the non-linear relationship between the mode coefficients and the boundary conditions. A trained surrogate model for modes coefficients prediction is obtained after a certain number of training iterations. Finally, the flow field is reconstructed by combining the product of the POD basis and coefficients. Based on the test dataset, an evaluation of the ROM is carried out. The evaluation results show that the proposed POD-ROM accurately describe the flow status of the fluid field in rod bundles with high resolution in only a few milliseconds.

  • https://doi.org/10.1016/j.net.2021.07.010 인용 PDF KSCI

High-fidelity numerical investigation on structural integrity of SFR fuel cladding during design basis events

  • Seo-Yoon Choi;Hyung-Kyu Kim;Min-Seop Song;Jae-Ho Jeong
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.359-374
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    • 2024

  • A high-fidelity numerical analysis methodology was proposed for evaluating the fuel rod cladding integrity of a Prototype Gen IV Sodium Fast Reactor (PGSFR) during normal operation and Design basis events (DBEs). The MARS-LMR code, system transient safety analysis code, was applied to analyze the DBEs. The results of the MARS-LMR code were used as boundary condition for a 3D computational fluid dynamics (CFD) analysis. The peak temperatures considering HCFs satisfied the cladding temperature limit. The temperature and pressure distributions were calculated by ANSYS CFX code, and applied to structural analysis. Structural analysis was performed using ANSYS Mechanical code. The seismic reactivity insertion SSE accident among DBEs had the highest peak cladding temperature and the maximum stress, as the value of 87 MPa. The fuel cladding had over 40 % safety margin, and the strain was below the strain limit. Deformation behavior was elucidated for providing relative coordinate data on each active fuel rod center. Bending deformation resulted in a flower shape, and bowing bundle did not interact with the duct of fuel assemblies. Fuel rod maximum expansion was generated with highest stress. Therefore, it was concluded that the fuel rod cladding of the PGSFR has sufficient structural safety margin during DBEs.

  • https://doi.org/10.1016/j.net.2023.10.007 인용 PDF

A Study of Flow Pattern in $5{\times}5$ Rod Bundle by the Spacer Grid Mixing Vane (지지격자 혼합날개에 의한 $5{\times}$ 5 봉다발에서 유동 패턴)

  • Choo, Yeon-Jun;Chang, Seok-Kyu;Kim, Bok-Deok;Moon, Sang-Ki;Song, Chul-Hwa
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2873-2878
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    • 2007

  • The mixing vanes attached to the spacer grid of rod bundles are used to improve the heat transfer in heat exchanger devices by controlling the characteristics of the flow structures and turbulence. In this study, velocity patterns induced by two types of mixing vane(split and swirl vane) are measured by the PIV technique to better understand how to effect on the cross and secondary vortex flow patterns in $5{\times}$ rod bundle simulating the fuel assembly of the nuclear reactor. A successful measurement of the lateral velocity patterns was conducted using a specially designed beam sheet generator and experimental loop at KAERI. As the result, we found that for the cross flow between subchannels, the split vane is more effective than the swirl vane, while for the secondary vortex flow in each subchannel, the swirl vane's one is larger and longer than split vane's one.

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