Fuzzy Adaptive Regularization Method for Inverse Steady-State Heat Transfer Problem

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Kun Wang ◽  
Guangjun Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Regularization Method ◽  
Thermal Boundary Condition ◽  
Transfer System ◽  
Steady State Heat ◽  
Heat Transfer System ◽  
Steady State Heat Transfer ◽  
Adaptive Ability ◽  
Fuzzy Adaptive

For the steady-state heat transfer process, a fuzzy adaptive regularization method (FARM) is proposed to estimate the distributed thermal boundary condition in heat transfer system. First, the relationship model between temperatures at measurement points and parameters to be estimated is established based on sensitivity matrix. The regularization term is introduced into the least-squares objective function, and then the distributed thermal boundary condition is estimated by optimizing the new objective function. A fuzzy inference mechanism is developed to ensure the adaptive ability of FARM in which the regularization parameter is updated based on the residual norm between calculated and measured temperatures at measurement points and the norm of inversion parameters. Taking the plate heat conduction system and fluid–solid conjugate heat transfer system as research objects, the effects of the parameter distribution, the number of measurement points, and measurement errors on the inversion results are discussed by numerical experiments, and comparison with the classical regularization method is also conducted. Results indicate that FARM exhibits a good adaptive ability.

Fuzzy Adaptive Predictive Inverse for Nonlinear Transient Heat Transfer Process

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Guangjun Wang ◽  
Yanhao Li ◽  
Hong Chen ◽  
Shibin Wan ◽  
Cai Lv
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Inverse Method ◽  
Fuzzy Inference ◽  
Relationship Matrix ◽  
Transfer System ◽  
Nonlinear Transient ◽  
Heat Transfer System ◽  
Adaptive Ability ◽  
Fuzzy Adaptive

For nonlinear transient heat transfer system, a fuzzy adaptive predictive inverse method (FAPIM) is proposed to inverse transient boundary heat flux. The influence relationship matrix is utilized to establish time-varying linear prediction model of the temperatures at measurement point. Then, the predictive and measurement temperatures are used to inverse the heat flux at current moment by rolling optimization. A decentralized fuzzy inference (DFI) mechanism is established. The deviation vector of the predictive temperature is adopted to conduct decentralized inference by a set of fuzzy inference units, and then, the influence relationship matrix is updated online to guarantee the adaptive ability of the prediction model by weighting fuzzy inference components. FAPIM is utilized to inverse the unknown heat flux of a heat transfer system with temperature-dependent thermal properties, which has shown that the inverse method has better adaptive ability for the inverse problems of nonlinear heat transfer system.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

scholarly journals Higher Order Multiscale Finite Element Method for Heat Transfer Modeling

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3827
Author(s):  
Marek Klimczak ◽  
Witold Cecot
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Higher Order ◽  
Shape Functions ◽  
Multiscale Finite Element Method ◽  
Multiscale Finite Element ◽  
Steady State Heat ◽  
Steady State Heat Transfer

In this paper, we present a new approach to model the steady-state heat transfer in heterogeneous materials. The multiscale finite element method (MsFEM) is improved and used to solve this problem. MsFEM is a fast and flexible method for upscaling. Its numerical efficiency is based on the natural parallelization of the main computations and their further simplifications due to the numerical nature of the problem. The approach does not require the distinct separation of scales, which makes its applicability to the numerical modeling of the composites very broad. Our novelty relies on modifications to the standard higher-order shape functions, which are then applied to the steady-state heat transfer problem. To the best of our knowledge, MsFEM (based on the special shape function assessment) has not been previously used for an approximation order higher than p = 2, with the hierarchical shape functions applied and non-periodic domains, in this problem. Some numerical results are presented and compared with the standard direct finite-element solutions. The first test shows the performance of higher-order MsFEM for the asphalt concrete sample which is subject to heating. The second test is the challenging problem of metal foam analysis. The thermal conductivity of air and aluminum differ by several orders of magnitude, which is typically very difficult for the upscaling methods. A very good agreement between our upscaled and reference results was observed, together with a significant reduction in the number of degrees of freedom. The error analysis and the p-convergence of the method are also presented. The latter is studied in terms of both the number of degrees of freedom and the computational time.

Preliminary design of EU DEMO helium-cooled breeding blanket primary heat transfer system

2018 ◽  
Vol 136 ◽  
pp. 1567-1571 ◽  
Author(s):  
I. Moscato ◽  
L. Barucca ◽  
S. Ciattaglia ◽  
P.A. Di Maio ◽  
G. Federici
Keyword(s):  
Heat Transfer ◽  
Preliminary Design ◽  
Transfer System ◽  
Heat Transfer System

scholarly journals Darcy-Brinkman free convection about a wedge and a cone subjected to a mixed thermal boundary condition

1992 ◽  
Vol 15 (4) ◽  
pp. 789-794 ◽  
Author(s):  
G. Ramanaiah ◽  
V. Kumaran
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Free Convection ◽  
Transformation Group ◽  
Darcy Number ◽  
Thermal Boundary Condition ◽  
High Porosity

The Darcy-Brinkman free convection near a wedge and a cone in a porous medium with high porosity has been considered. The surfaces are subjected to a mixed thermal boundary condition characterized by a parameterm;m=0,1,∞correspond to the cases of prescribed temperature, prescribed heat flux and prescribed heat transfer coefficient respectively. It is shown that the solutions for differentmare dependent and a transformation group has been found, through which one can get solution for anymprovided solution for a particular value ofmis known. The effects of Darcy number on skin friction and rate of heat transfer are analyzed.

Numerical Simulation on Heat Dissipating Performance of New Pipe with Grid Plate

2012 ◽  
Vol 532-533 ◽  
pp. 417-421
Author(s):  
Chang Li Song ◽  
Jing Ji
Keyword(s):  
Heat Transfer ◽  
Simulation Analysis ◽  
Heat Transfer Analysis ◽  
Finite Element Software ◽  
Grid Plate ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Energy Conservation Law ◽  
Optimal Diameter ◽  
Selection Of

In order to improve the pipe dissipating area, a kind of new pipe with grid plate is proposed in this paper. Based on the basic principle of heat transfer and energy conservation law, by finite element software ANSYS the simulation analysis of the steady-state heat transfer of the new pipeline is carried out, process of ANSYS modeling, loading and solving is introduced in detail, the distribution of temperature and stress for pipe with a grid plate is given, these can provide the foundation for the selection of the optimal diameter of the grid plate and transient heat transfer analysis of pipe.

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