Fuel Particle Heat Transfer Part 2: Radiation and Convection during Spreading Laboratory Fires

2022 ◽  
pp. 1-27
Author(s):  
Jack D Cohen ◽  
Mark A Finney
Keyword(s):  
Heat Transfer ◽  
Fuel Particle

Experimental Study on Heat Transfer of Fuel-Particle Mixtures in a Vertical Tube at Supercritical Pressure

2013 ◽  
Author(s):  
Xiao-Yu Wu ◽  
Dan Huang ◽  
Wei Li ◽  
Guo-Qiang Xu ◽  
Zhi Tao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Cooling System ◽  
High Heat ◽  
Vertical Tube ◽  
Solid Particles ◽  
Fuel Particle ◽  
High Heat Flux ◽  
Step Method ◽  
Working Pressure

Regenerative cooling system is thought to be an effective and practical solution to better thermal management for high heat flux applications. In this paper, we examined the effects of solid particles mixed with fuels on the heat transfer performances of supercritical fuel coolant. Two-step method was applied to prepare Fe3O4-kerosene fluids. Experiments were carried out to study the heat transfer characteristics of fuel-particle mixtures flowing in a vertical tube at supercritical pressures. Results show that there are three different heat transfer mechanisms at the in-, mid- and ex-sections along the tube; increasing the flow rate or the working pressure could enhance the heat transfer performances, yet higher heat flux leads to poorer heat transfer performances. Besides, the addition of solid particles deteriorates the heat transfer performances of the fuel coolant through the modification of inner wall surfaces. As the particle content increases, the heat transfer performance becomes worse.

A Modeling Analysis of Non-Melting Solid Fuel Particle Heating

2003 ◽  
Author(s):  
Ali A. Rostami ◽  
Susan E. Wrenn ◽  
Mohammad R. Hajaligol
Keyword(s):  
Heat Transfer ◽  
Weight Loss ◽  
Solid Particle ◽  
Convection Heat Transfer ◽  
Total Weight ◽  
Fuel Particle ◽  
Total Weight Loss ◽  
Convection Heat ◽  
Particle Heating ◽  
Internal Convection

The heating of fuel particles is generally the first step in the process of gasification or combustion of solid fuels such as coal and biomass. The particle heating that is achieved via combined convection and radiation effects requires a rigorous analysis of heat transfer within as well as outside of the particle, which makes the lumped capacity approximation unsuitable. A more adequate representation of the heating-up process requires the inclusion of the internal convection within the solid particle, the blowing effects on the particle surface, the spatial and temporal variations of the solid thermal conductivity as well as the heat of pyrolysis reactions. The internal convection tends to equalize the temperature distribution within the solid, while the blowing effect contributes to the boundary layer thickening and eventually to a reduction in the convection heat transfer to the particle. To include the above-mentioned effects, a kinetic model for the total weight loss of the solid material was coupled with the heating model. A simple first-order reaction model for the total weight loss was utilized in this study. For materials with high moisture contents, the heat of pyrolysis reactions is an important factor in the heating rate and non-uniform heating of the solid particle. Thermal equilibrium between the solid and evolved gases was assumed within the particle and the equations for the conservation of mass and energy were solved numerically. Results show that surface blowing which is due to the devolatilization of the particle tends to reduce the convection heat transfer from the hot gases to the particle. Internal convection contributes to thermal uniformity in the particle. Heat of pyrolysis reactions plays an important role in the heating profile of the particle. It delays the temperature rise of the particle until most of the volatile materials is released.

Multiscale analysis of heat transfer in coated fuel particle compacts – Application to the HTTR

2015 ◽  
Vol 282 ◽  
pp. 106-115 ◽  
Author(s):  
X. Garnaud ◽  
X. Han ◽  
P. Jacquet ◽  
J.-M. Ndombo ◽  
I. Limaiem
Keyword(s):  
Heat Transfer ◽  
Multiscale Analysis ◽  
Fuel Particle ◽  
Coated Fuel Particle

Development of Local Heat Transfer Models for the Safety Assessment of Prismatic Modular High Temperature Gas-Cooled Reactor Cores

2008 ◽  
Author(s):  
Richard Stainsby ◽  
Matthew Worsley ◽  
Frances Dawson ◽  
Joakim Baker ◽  
Andrew Grief ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Effective Conductivity ◽  
Heat Removal ◽  
Finite Element Simulations ◽  
Normal Operation ◽  
Scale Model ◽  
Fuel Particle ◽  
Multi Scale ◽  
Fuel Elements

This paper presents a model developed for determining fuel particle and fuel block temperatures of a prismatic core modular reactor during both normal operation and under fault conditions. The model is based on multi-scale modeling techniques and has been qualified by comparison with finite element simulations for both steady state and transient conditions. Further, a model for determining the effective conductivity of the block fuel elements — important for heat removal in loss of flow conditions — is presented and, again, qualified by comparison with finite element simulations. A numerical model for predicting conduction heat transfer both within and between block fuel elements has been developed which, when coupled with the above multi-scale model, allows simulations of whole cores to be carried out whilst retaining the ability to predict the temperatures of individual coolant channels and individual coated particles in the fuel if required. This ability to resolve heat transfer on length scales ranging from a few meters down to a few microns within the same model is very powerful and allows a complete assessment of the fuel and structural temperatures within a core to be made. More significantly, this level of resolution facilitates interactive coupling with neutronics models to enable the strong temperature/reactivity feedbacks, inherent in such cores, to be resolved correctly.

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