Effect of Radiative Heat Transfer and Boundary Conditions on the Airflow and Temperature Distribution Inside a Heated Tunnel Greenhouse

2018 ◽  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Radiative Heat Transfer ◽  
Radiative Heat

Implementation of the PN-Approximation for Radiative Heat Transfer on OpenFOAM

2013 ◽  
Author(s):  
Ricardo Marquez ◽  
Michael Modest
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Variable Properties ◽  
3 Dimensional ◽  
Coupled Partial Differential Equations ◽  
Invariance Properties ◽  
Geometric Invariance ◽  
Benchmark Solutions

This work presents an OpenFOAM implementation of the PN approximation for radiative heat transfer, including higher orders P3, P5, and P7. Also described is a procedure which enables the sequential numerical computations of the coupled partial differential equations (PDEs) by re-expressing the boundary conditions in matrix form so that individual boundary conditions can be associated with each PDE. The implementation of the software programs are verified with derived analytical solutions for 1-D slabs with constant and variable properties, and are also tested with various orientations in order to demonstrate the geometric invariance properties of the 3-dimensional PN formulation. A few examples taken from the literature are also considered in this work and could be taken as benchmark solutions for the PN approximations.

Effect of Radiative Heat Transfer Factor on the Temperature Distribution of a First Stage Vane

2014 ◽  
Author(s):  
Hong Yin ◽  
Mingfei Li ◽  
Zhongran Chi ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Swirling Flow ◽  
Inlet Temperature ◽  
Radiative Effect ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet

As the advanced heavy-duty gas turbine develops, the turbine inlet temperature and pressure have increased quite significantly to achieve better performance. The flow and heat transfer conditions of hot components including combustor and turbine become even more extreme than ever which need corresponding aerodynamic and cooling design development. The issue of combustor-turbine interaction has been proposed as a complicated research topic. Currently the hot streak, turbulence intensity, swirling flow, radiation are the four important factors for combustor-turbine interaction research according to the literature. Especially as the turbine inlet temperature increases, the radiative heat transfer plays a more and more important role. In this paper, a first stage vane is selected for the conjugate heat transfer simulation including radiative heat transfer since it is almost impossible to identify the radiative effect in experiment. The goal is to examine the effects of radiative heat flux and temperature increment caused by radiation. Several radiative factors including the inlet radiation, gas composition, vane surface emissivity and outlet reflection are investigated. The temperature distribution and heat flux enhancement under different conditions are compared, which can provide reference to the turbine heat transfer design. The general information of radiative effect can be summarized by quantitative analysis. Results show that the temperature increases obviously when considering the radiation effect as expected. However, these factors show distinct influence on the vane temperature distribution. The inlet radiation has significant impact on the vane leading edge and pressure side. Besides the gas radiation plays quite uniform on the whole vane surface.

The Role of Radiative Heat Transfer With Participating Gases on the Temperature Distribution in Solid Oxide Fuel Cells

2004 ◽  
Author(s):  
J. D. J. VanderSteen ◽  
J. G. Pharoah
Keyword(s):  
Heat Transfer ◽  
Fuel Cells ◽  
Temperature Distribution ◽  
Solid Oxide Fuel Cells ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Transport Processes ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Participating Media

Solid oxide fuel cell (SOFC) technology has been shown to be viable, but its profitability has not yet been seen. To achieve a high net efficiency at a low net cost, a detailed understanding of the transport processes both inside and outside of the SOFC stack is required. Of particular significance is an accurate determination of the temperature distribution because material properties, chemical kinetics and transport properties depend heavily on the temperature. Effective utilization of the heat can lead to a substantial increase in overall system efficiency and decrease in operating cost. Despite the extreme importance in accurately predicting temperature, the majority of SOFC modeling work ignores radiative heat transfer. SOFCs operate at temperatures around or above 1200 K, where radiation effects can be significant. In order to correctly predict the radiation heat transfer, participating gases must also be included. Water vapour and carbon dioxide can absorb, emit, and scatter radiation, and are present at the anode in high concentrations. This paper presents a thermal transport model for analyzing heat transfer and improving thermal management within planar SOFCs. The model was implemented using a commercial computational fluid dynamic (CFD) code and includes conduction, convection, and radiation in a participating media. It is clear from this study that radiation must be considered when modelling solid oxide fuel cells. The effect of participating media radiation was shown to be minimal in this geometry, but it is likely to be more important in tubular geometries.

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