Thermal Response of Open-Cell Porous Materials: A Numerical Study and Model Assessment

Irick, Kevin; Fathi, Nima

doi:10.1115/vvs2018-9317

Cited by 4 publications

(4 citation statements)

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“…Thus, systematic mesh refinement here approximately halves the characteristic mesh size from mesh H+1 to mesh H. The domain discretization is used with a second order accurate Galerkin Finite Element Method (FEM) approach which is employed to solve Eq. (4) over the entire domain [15]. In short, Eq.…”

Section: Each T Th Triangle Is Configured With Three Vertices Such Thmentioning

confidence: 99%

Computational Evaluation of Thermal Barrier Coatings

Irick¹,

Fathi²

2020

Preprint

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In the power plant industry, the turbine inlet temperature (TIT) plays a key role in the efficiency of the gas turbine and, therefore, the overall-in most cases combined-thermal power cycle efficiency. Gas turbine efficiency increases by increasing TIT. However, an increase of TIT would increase the turbine component temperature which can be critical (e.g., hot gas attack). Thermal barrier coatings (TBCs)-porous media coatings-can avoid this case and protect the surface of the turbine blade. This combination of TBC and film cooling produces a better cooling performance than conventional cooling processes. The effective thermal conductivity of this composite is highly important in design and other thermal/structural assessments. In this article, the effective thermal conductivity of a simplified model of TBC is evaluated. This work details a numerical study on the steady-state thermal response of two-phase porous media in two dimensions using personal finite element analysis (FEA) code. Specifically, the system response quantity (SRQ) under investigation is the dimensionless effective thermal conductivity of the domain. A thermally conductive matrix domain is modeled with a thermally conductive circular pore arranged in a uniform packing configuration. Both the pore size and the pore thermal conductivity are varied over a range of values to investigate the relative effects on the SRQ. In this investigation, an emphasis is placed on using code and solution verification techniques to evaluate the obtained results. The method of manufactured solutions (MMS) was used to perform code verification for the study, showing the FEA code to be second-order accurate. Solution verification was performed using the grid convergence index (GCI) approach with the global deviation uncertainty estimator on a series of five systematically refined meshes for each porosity and thermal conductivity model configuration. A comparison of the SRQs across all domain configurations is made, including uncertainty derived through the GCI analysis. Subscripts C= cold

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Section: Each T Th Triangle Is Configured With Three Vertices Such Thmentioning

confidence: 99%

Computational Evaluation of Thermal Barrier Coatings

Irick¹,

Fathi²

2020

Preprint

Self Cite

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“…Using k2/k1=1 for convenience for the MMS study, the pO,H value for mesh H of each system configuration was expected to converge to 2, representing pf. A full, detailed description of the theory behind the code verification used in this study is explained in [21] and [22].…”

Section: Codementioning

confidence: 99%

High-Fidelity Calculation of Effective Thermal Response of Composite Media With Heat Generation Source

Irick

Fathi

2020

ASME 2020 Verification and Validation Symposium

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The complexity of conductive heat transfer in a structure increases with heterogeneity (e.g., multi-component solid-phase systems with a source of internal thermal heat generation). Any discontinuity of material property — especially thermal conductivity — would warrant a thorough analysis to evaluate the thermal behavior of the system of interest. Heterogeneous thermal conditions are crucial to heat transfer in nuclear fuel assemblies, because the thermal behavior within the assemblies is governed significantly by the heterogeneous thermal conditions at both the system and component levels. A variety of materials have been used as nuclear fuels, the most conventional of which is uranium dioxide, UO2. UO2 has satisfactory chemical and irradiation tolerances in thermal reactors, whereas the low thermal conductivity of porous UO2 can prove challenging. Therefore, the feasibility of enhancing the thermal conductivity of oxide fuels by adding a high-conductivity secondary solid component is still an important ongoing topic of investigation. Undoubtedly, long-term, stable development of clean nuclear energy would depend on research and development of innovative reactor designs and fuel systems. Having a better understanding of the thermal response of the unit cell of a composite that represents a fuel matrix cell would help to develop the next generation of nuclear fuel and understand potential performance enhancements. The aim of this article is to provide an assessment of a high-fidelity computational model response of heterogeneous materials with heat generation in circular fillers. Two-dimensional, steady-state systems were defined with a circular, heat-generating filler centered in a unit-cell domain. A Fortran-based finite element method (FEM) code was used to solve the heat equation on an unstructured triangular mesh of the systems. This paper presents a study on the effects of a heat-generating filler material’s relative size and thermal conductivity on effective thermal conductance, Geff, within a heterogenous material. Code verification using the method of manufactured solution (MMS) was employed, showing a second-order accurate numerical implementation. Solution verification was performed using a global deviation grid convergence index (GCI) method to assess solution convergence and estimate solution numerical uncertainty, Unum. Trend results are presented, showing variable response in Geff to filler size and thermal conductivity.

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“…The domain discretization is used with a second order accurate Galerkin Finite Element Method (FEM) approach which is employed to solve Eq. (4) over the entire domain [11]. In short, Eq.…”

Section: Discretizationmentioning

confidence: 99%

Computational Evaluation of Thermal Barrier Coatings: Two-Phase Thermal Transport Analysis

Irick

Fathi

2019

ASME 2019 Verification and Validation Symposium

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In the power plant industry, the turbine inlet temperature (TIT) plays a key role in the efficiency of the gas turbine and, therefore, the overall — in most cases combined — thermal power cycle efficiency. Gas turbine efficiency increases by increasing TIT. However, an increase of TIT would increase the turbine component temperature which can be critical (e.g., hot gas attack). Thermal barrier coatings (TBCs) — porous media coatings — can avoid this case and protect the surface of the turbine blade. This combination of TBC and film cooling produces a better cooling performance than conventional cooling processes. The effective thermal conductivity of this composite is highly important in design and other thermal/structural assessments. In this article, the effective thermal conductivity of a simplified model of TBC is evaluated. This work details a numerical study on the steady-state thermal response of two-phase porous media in two dimensions using personal finite element analysis (FEA) code. Specifically, the system response quantity (SRQ) under investigation is the dimensionless effective thermal conductivity of the domain. A thermally conductive matrix domain is modeled with a thermally conductive circular pore arranged in a uniform packing configuration. Both the pore size and the pore thermal conductivity are varied over a range of values to investigate the relative effects on the SRQ. In this investigation, an emphasis is placed on using code and solution verification techniques to evaluate the obtained results. The method of manufactured solutions (MMS) was used to perform code verification for the study, showing the FEA code to be second-order accurate. Solution verification was performed using the grid convergence index (GCI) approach with the global deviation uncertainty estimator on a series of five systematically refined meshes for each porosity and thermal conductivity model configuration. A comparison of the SRQs across all domain configurations is made, including uncertainty derived through the GCI analysis.

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Thermal Response of Open-Cell Porous Materials: A Numerical Study and Model Assessment

Cited by 4 publications

References 0 publications

Computational Evaluation of Thermal Barrier Coatings

Computational Evaluation of Thermal Barrier Coatings

High-Fidelity Calculation of Effective Thermal Response of Composite Media With Heat Generation Source

Computational Evaluation of Thermal Barrier Coatings: Two-Phase Thermal Transport Analysis

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