Use of Fuel Assembly/Backfill Gas Effective Thermal Conductivity Models to Predict Basket and Fuel Cladding Temperatures Within a Rail Package During Normal Transport

Two-dimensional finite element thermal simulations of a generic rail package designed to transport twenty-one spent PWR assemblies were performed for normal transport conditions. Effective thermal conductivity models were employed within the fuel assembly/backfill gas region. Those conductivity models were developed by other investigators assuming the basket wall temperature is uniform. They are typically used to predict the maximum fuel cladding temperature near the package center. The cladding temperature must not exceed specified limits during normal transport. This condition limits the number and heat generation rate of fuel assembles that can transported. The current work shows the support basket wall temperatures in the periphery of the package are highly non-uniform. Moreover the thermal resistance of those regions significantly affects the maximum fuel clad temperature near the package center. This brings the validity of the fuel/backfill gas thermal conductivity models into question. The non-uniform basket wall temperature profiles quantified in this work will be used in future numerical and experimental studies to develop new thermal models of the fuel assembly/backfill gas regions. This will be an iterative process, since the assembly/backfill model affects the predicted basket wall temperature profiles.

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Analytical and numerical assessment of the effect of highly conductive inclusions distribution on the thermal conductivity of particulate composites

Journal of Composite Materials ◽

10.1177/0021998319843329 ◽

2019 ◽

Vol 53 (25) ◽

pp. 3499-3514 ◽

Cited By ~ 2

Author(s):

Kamran A Khan ◽

Falah Al Hajeri ◽

Muhammad A Khan

Keyword(s):

Thermal Conductivity ◽

Effective Thermal Conductivity ◽

Numerical Models ◽

Random Network ◽

Experimental Studies ◽

Percolation Model ◽

Spherical Particles ◽

Particulate Composites ◽

Advanced Composites ◽

Micromechanical Models

Highly conductive composites have found applications in thermal management, and the effective thermal conductivity plays a vital role in understanding the thermo-mechanical behavior of advanced composites. Experimental studies show that when highly conductive inclusions embedded in a polymeric matrix the particle forms conductive chain that drastically increase the effective thermal conductivity of two-phase particulate composites. In this study, we introduce a random network three dimensional (3D) percolation model which closely represent the experimentally observed scenario of the formation of the conductive chain by spherical particles. The prediction of the effective thermal conductivity obtained from percolation models is compared with the conventional micromechanical models of particulate composites having the cubical arrangement, the hexagonal arrangement and the random distribution of the spheres. In addition to that, the capabilities of predicting the effective thermal conductivity of a composite by different analytical models, micromechanical models, and, numerical models are also discussed and compared with the experimental data available in the literature. The results showed that random network percolation models give reasonable estimates of the effective thermal conductivity of the highly conductive particulate composites only in some cases. It is found that the developed percolation models perfectly represent the case of conduction through a composite containing randomly suspended interacting spheres and yield effective thermal conductivity results close to Jeffery's model. It is concluded that a more refined random network percolation model with the directional conductive chain of spheres should be developed to predict the effective thermal conductivity of advanced composites containing highly conductive inclusions.

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Design of High Thermal Conductivity Particle Filled Polymer Using Effective Thermal Conductivity Models

Materials Science Forum ◽

10.4028/www.scientific.net/msf.714.21 ◽

2012 ◽

Vol 714 ◽

pp. 21-24 ◽

Cited By ~ 1

Author(s):

B. Garnier ◽

F. Danes

Keyword(s):

Thermal Conductivity ◽

Effective Thermal Conductivity ◽

Thermal Contact Resistance ◽

Volume Fraction ◽

Thermal Contact ◽

Analytical Models ◽

Finite Element Models ◽

Inner Diameter ◽

Conductive Particles ◽

Conductivity Models

The context of this work is the enhancement of the thermal conductivity of polymer by adding conductive particles. It will be shown how we can use effective thermal conductivity models to investigate effect of various factors such as the volume fraction of filler, matrix thermal conductivity, thermal contact resistance, and inner diameter for hollow particles. Analytical models for lower bounds and finite element models will be discussed. It is shown that one can get some insights from effective thermal conductivity models for the tailoring of conductive composite, therefore reducing the amount of experimental work.

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Development of effective thermal conductivity models for Reserve Shutdown Control fuel block of prismatic HTGR for hydrogen production

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2017.04.128 ◽

2017 ◽

Vol 42 (29) ◽

pp. 18614-18625 ◽

Cited By ~ 1

Author(s):

Dong-Ho Shin ◽

Su-Jong Yoon ◽

Hyoung Kyu Cho ◽

Goon-Cherl Park ◽

Taewan Kim

Keyword(s):

Thermal Conductivity ◽

Hydrogen Production ◽

Effective Thermal Conductivity ◽

Conductivity Models

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Effective Thermal Conductivity of Ordered Mesoporous Carbon CMK-3

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Theory and Fundamental Research in Heat Transfer ◽

10.1115/ht2013-17334 ◽

2013 ◽

Author(s):

Daili Feng ◽

Yanhui Feng ◽

Xinxin Zhang ◽

Ge Wang

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Effective Thermal Conductivity ◽

Mesoporous Carbon ◽

Two Dimensional ◽

Hexagonal Array ◽

Coupled Heat Transfer ◽

Ordered Mesoporous ◽

Carbon Rods ◽

Conductivity Models

CMK-3 is a typical of carbon rods which are arranged in relatively regular two-dimensional hexagonal array. In our study, the effective thermal conductivity of CMK-3 composite is investigated. For the thermal conductivity of carbon rods, the equilibrium molecular dynamics (EMD) is performed with Tersoff potential. The influences of porosity and temperature are also considered. For the thermal conductivity of air confined in mesoporous can be estimated by the frequently used Kaganer model. Then, the effective thermal conductivity models developed for coupled heat transfer of air and solid are obtained by the unit cell method. ETCs along the X and Y directions are extremely poor, due to the overwhelming effect of air thermal resistance. However, in the Z direction, the ETC improves almost linearly as the porosity decreases, and the value is much higher than those of X and Y directions. This study is in attempts to explore the possibility of CMK-3 being a proper substrate for thermal usage.

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Measurements of the Intrinsic Thermal Conductivity of Individual Multi-Wall Carbon Nanotubes

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44340 ◽

2011 ◽

Author(s):

Juekuan Yang ◽

Scott W. Waltermire ◽

Yang Yang ◽

Deyu Li ◽

Yunfei Chen

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotubes ◽

Heat Source ◽

Thermal Resistance ◽

Effective Thermal Conductivity ◽

Experimental Studies ◽

Contact Thermal Resistance ◽

Multi Wall Carbon Nanotubes ◽

The Past ◽

Thermal Conductivities

Thermal transport through carbon nanotubes (CNTs) attracted a lot of attention over the past decade. Several experimental studies have been carried out to determine the thermal conductivities of CNTs [1–3]. However, the measurements are based on an individual CNT sample between two suspended membranes and the results actually include both the intrinsic thermal resistance of the CNT and the contact thermal resistance between the CNT and the two suspended membranes that serve as a heat source and a heat sink. Hence, the effective thermal conductivity extracted from these measurements should be lower than the intrinsic thermal conductivities of the CNTs measured. To minimize the contact thermal resistance, electron beam induce deposition (EBID) of different metals has been used to increase the contact area between the CNT and the heat source and sink [3,4]. However, it is still not clear how effective this treatment is and to what level the effective thermal conductivity obtained after the EBID treatment reflects the intrinsic one.

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Thermal Dispersion in Porous Media—A Review on the Experimental Studies for Packed Beds

Applied Mechanics Reviews ◽

10.1115/1.4024351 ◽

2013 ◽

Vol 65 (3) ◽

Cited By ~ 19

Author(s):

Türküler Özgümüş ◽

Moghtada Mobedi ◽

Ünver Özkol ◽

Akira Nakayama

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Porous Media ◽

Effective Thermal Conductivity ◽

Experimental Studies ◽

Experimental Methods ◽

Packed Beds ◽

Thermal Dispersion ◽

Heat Addition

Thermal dispersion is an important topic in the convective heat transfer in porous media. In order to determine the heat transfer in a packed bed, the effective thermal conductivity including both stagnant and dispersion thermal conductivities should be known. Several theoretical and experimental studies have been performed on the determination of the effective thermal conductivity. The aim of this study is to review the experimental studies done on the determination of the effective thermal conductivity of the packed beds. In this study, firstly brief information on the definition of the thermal dispersion is presented and then the reported experimental studies on the determination of the effective thermal conductivity are summarized and compared. The reported experimental methods are classified into three groups: (1) heat addition/removal at the lateral boundaries, (2) heat addition at the inlet/outlet boundary, (3) heat addition inside the bed. For each performed study, the experimental details, methods, obtained results, and suggested correlations for the determination of the effective thermal conductivity are presented. The similarities and differences between experimental methods and reported studies are shown by tables. Comparison of the correlations for the effective thermal conductivity is made by using figures and the results of the studies are discussed.

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