scholarly journals Modelling of Radiative Heat Transfer in Modelica with a Mobile Solar Radiation Model and a View Factor Model

2012 ◽  
Author(s):  
Arnav Pathak ◽  
Victor Norrefeldt ◽  
Gunnar Grün
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Factor Model ◽  
View Factor ◽  
Radiation Model ◽  
Solar Radiation Model

scholarly journals A Deep Neural Network Model of Particle Thermal Radiation in Packed Bed

2020 ◽  
Vol 34 (01) ◽  
pp. 1029-1036
Author(s):  
Hao Wu ◽  
Shuang Hao
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Thermal Radiation ◽  
Radiative Heat Transfer ◽  
Power Plants ◽  
Deep Neural Network ◽  
Radiative Heat ◽  
Particle Packing ◽  
View Factor ◽  
Pebble Bed

Prediction of particle radiative heat transfer flux is an important task in the large discrete granular systems, such as pebble bed in power plants and industrial fluidized beds. For particle motion and packing, discrete element method (DEM) now is widely accepted as the excellent Lagrangian approach. For thermal radiation, traditional methods focus on calculating the obstructed view factor directly by numerical algorithms. The major challenge for the simulation is that the method is proven to be time-consuming and not feasible to be applied in the practical cases. In this work, we propose an analytical model to calculate macroscopic effective conductivity from particle packing structures Then, we develop a deep neural network (DNN) model used as a predictor of the complex view factor function. The DNN model is trained by a large dataset and the computational speed is greatly improved with good accuracy. It is feasible to perform real-time simulation with DNN model for radiative heat transfer in large pebble bed. The trained model also can be coupled with DEM and used to analyze efficiently the directional radiative conductivity, anisotropic factor and wall effect of the particle thermal radiation.

Temperature Variation of Concrete-Steel Deck Plate under Solar Radiation

2010 ◽  
Vol 44-47 ◽  
pp. 158-162
Author(s):  
Bo Chen ◽  
Jin Zheng ◽  
Jian Ping Wang
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Temperature Variation ◽  
Heat Transfer Analysis ◽  
Time Varying ◽  
Radiation Model ◽  
Deck Plate ◽  
Solar Radiation Model ◽  
Steel Deck

The analysis of time-varying temperature field of a composite concrete-steel deck plate under strong solar radiation is carried out in this study. By assuming the temperature distribution along the bridge longitudinal direction is basically constant, one typical segment of the deck plate is investigated. Two-dimensional heat transfer models are utilized to determine the time-dependent temperature distribution of deck plate, deck trough and deck pavement of the bridge. A modified solar radiation model is utilized to predict the variation of solar radiation in a whole day. A thermodynamic model is established and a transient heat transfer analysis is conducted to predict the time-varying temperature distribution of the deck plate at different time. The measured ambient temperature data are used as thermal boundary conditions during the numerical analysis. The made observations demonstrate that the simulated temperature variation of the deck plate based on the modified solar radiation model agrees well with measurement results, as compared with those obtained from the traditional solar radiation model..

Coupling a Discrete Transfer Method to a View Factors Technique for Radiative Heat Transfer Modeling in Industrial Furnaces

2005 ◽  
Author(s):  
Youssef Joumani ◽  
Guillaume Mougin ◽  
Fouad Ammouri ◽  
Marc Till
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Three Dimensional ◽  
Analytical Formula ◽  
Two Dimensions ◽  
Radiation Model ◽  
Participating Media ◽  
View Factors ◽  
Transfer Method

Air Liquide has been involved in the design of industrial furnaces (glass melting, reheating, aluminum, …) for several years. Thanks to that experience, known-how and expertise in modeling such applications have been developed. Dedicated simulation tools — 0D for global heat and mass balance, 1D for the prediction of longitudinal temperature profiles and 3D for detailed analysis — have been built. Each of them is very helpful when used relevantly and offers numerous opportunities at each step of the design of a furnace. In such kind of applications, the temperature levels are very high (up to 2500 K). As a consequence it is very crucial to simulate the radiative heat transfer as accurately as possible. This requires the use of a radiation model that can take into account complex geometries, non-isothermal media and various gas mixture compositions. Very often, three-dimensional simulations are necessary and reduction to smaller dimension problems is difficult or inadequate. The present paper introduces a new radiation model for computing two-dimensionally radiative heat transfer in an industrial furnace with a piecewise distributed load. To reduce the three-dimensional problem to two dimensions, the method consists in coupling the 2D radiation transport equation to a boundary condition based on view factors through an imaginary plane to homogenize the radiative behavior of the load surface. A solution procedure using the discrete transfer method associated to a weighted-sum-of-gray-gases database to deal with absorption and emission of a CO2-H2O mixture is proposed. Simulation results are finally compared to an analytical formula and then to a full-3D approach taking into account participating media, non-isothermal and gray walls. All tests show that this model can be used to simulate industrial configurations with a good accuracy.

Numerical Modeling of Radiative Heat Transfer in Pool Fire Simulations

2005 ◽  
Author(s):  
G. Krishnamoorthy ◽  
S. Borodai ◽  
R. Rawat ◽  
J. Spinti ◽  
P. J. Smith
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Pool Fire ◽  
Computational Time ◽  
Discrete Ordinates ◽  
Absorption Coefficients ◽  
Radiation Model ◽  
Discrete Ordinates Method ◽  
Property Model

Different approaches to modeling radiative heat transfer in Large Eddy Simulations (LES) of a 38 cm diameter methane pool fire are compared. The P-1 radiation model and the discrete ordinates method are spatially decomposed to solve the radiative transport equation (RTE) on parallel computers. The radiative properties are obtained in the form of mean absorption coefficients from total emissivity data or of spectral absorption coefficients extracted from a narrow band model (RADCAL). The predictions are compared with experimental data. The different approaches are able to predict total radiative heat loss fractions with only a moderate loss of accuracy. However, only the discrete ordinates method is able to qualitatively predict the distributions of the radiative heat flux vectors in regions away from the fire. Results obtained from the calculations performed with the gray property model are very close to those obtained with non-gray calculations. Employing the P-1 radiation model with the gray property model provides adequate coupling between the hydrodynamics and radiative heat transfer while decreasing computational time by about 20% compared to the discrete ordinates method in moderate size grids. The computational savings associated with the P-1 model can become significant in LES calculations that are performed on large computational grids (employing hundreds to thousands of processors) to resolve structures on the scale of the pool diameter. Such resolution is necessary to capture both the large structures on the scale of the pool fire and the smaller regions of air engulfments and visible flame structures that are pivotal to characterizing soot location and temperature.

scholarly journals Assessment on Time-Varying Thermal Loading of Engineering Structures Based on a New Solar Radiation Model

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Bo Chen ◽  
Yu-zhou Sun ◽  
Gan-jun Wang ◽  
Ling-yan Duan
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Thermal Loading ◽  
Measurement Data ◽  
Longitudinal Direction ◽  
Heat Transfer Analysis ◽  
Radiation Model ◽  
Engineering Structures ◽  
Temperature Distributions ◽  
Solar Radiation Model

This paper aims to carry out the condition assessment on solar radiation model and thermal loading of bridges. A modification factor is developed to change the distribution of solar intensities during a whole day. In addition, a new solar radiation model for civil engineering structures is proposed to consider the shelter effects induced by cloud, mountains, and surrounding structures. The heat transfer analysis of bridge components is conducted to calculate the temperature distributions based on the proposed new solar radiation model. By assuming that the temperature along the bridge longitudinal direction is constant, one typical bridge segment is specially studied. Fine finite element models of deck plates and corrugate sheets are constructed to examine the temperature distributions and thermal loading of bridge components. The feasibility and validity of the proposed solar radiation model are investigated through detailed numerical simulation and parametric study. The numerical results are compared with the field measurement data obtained from the long-term monitoring system of the bridge and they shows a very good agreement in terms of temperature distribution in different time instants and in different seasons. The real application verifies effectiveness and validity of the proposed solar radiation and heat transfer analysis.

scholarly journals Method for calculation of radiative heat transfer in beds of spherical particles

2020 ◽  
Vol 63 (6) ◽  
pp. 680-688
Author(s):  
A. I. Malinouski
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Direct Calculation ◽  
Computational Effort ◽  
Spherical Particles ◽  
Radiative Heat Flux ◽  
View Factor ◽  
Discrete Elements

A new technique for implementing external (particle-to-wall) and particle-to-particle radiative heat transfer in discrete elements method (DEM) simulations is proposed. It is based on the idea that an expected view factor value depends on relevant local bed parameters (distance between particles, particle radius ratio, and local bed porosity). Calculation of average view factors via the formula requires considerably less computational effort than direct in situ integration, when this happens a reasonable average value and an overall accuracy comparable to direct calculation are provided. Both mono- and polydisperse mixtures of spherical opaque particles were considered. It was shown that using nondimensional parameters, a simple general dependence for an external radiative heat flux may be introduced. Exponential and linear fits were proposed for estimating the particle-particle radiative heat flux. The generalization of the obtained formulas for various bed porosities is proposed. The distribution of cumulative transferred heat flux across the particles up to a certain distance was found, and the recommendations regarding the choice of that parameter to achieve a desired accuracy were formulated. Also, the method to account for the particle emissivity was proposed on the basis of the empirical dependence between emissivity and radiative heat flux in porous materials. The proposed method satisfies all the requirements to become a standard implementation of radiative heat transfer calculation in DEM.

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