Influence of Radiative Heat Transfer on Variation of Cell Voltage Within a Stack

2003 ◽  
Author(s):  
A. C. Burt ◽  
I. B. Celik ◽  
R. S. Gemmen ◽  
A. V. Smirnov
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Flow Distribution ◽  
Cell Voltage ◽  
Uniform Flow ◽  
Transfer Model ◽  
Computational Performance ◽  
Uniform Flow Distribution ◽  
The Impact

In this study, a numerical investigation of cell-to-cell voltage variation by considering the impact of flow distribution and heat transfer on a stack of cells has been performed. A SOFC stack model has been previously developed to study the influence of flow distribution on stack performance (Burt, et al., 2003). In the present study the heat transfer model has been expanded to include the influence of radiative heat transfer between the PEN (positive electrode, electrolyte, negative electrode) and the neighboring separator plates. Variations in cell voltage are attributed to asymmetries in stack geometry and nonuniformity in flow rates. Simulations were done in a parallel computing environment with each cell computed in a separate (CPU) process. This natural decomposition of the fuel cell stack reduced the number of communicated variables thereby improving computational performance. The parallelization scheme implemented utilized a message passing interface (MPI) protocol where cell-to-cell communication is achieved via exchange of temperature and thermal fluxes between neighboring cells. Inclusion of radiative heat transfer resulted in more uniform temperature and voltage distribution for cases of uniform flow distribution. Non-uniform flow distribution still resulted in significant cell-to-cell voltage variations.

Development of Radiative Heat Transfer Model for Pulverized Coal Combustion

2008 ◽  
Vol 34 (3) ◽  
pp. 344-350 ◽  
Author(s):  
Toshimitsu Asotani ◽  
Toru Yamashita ◽  
Hiroaki Tominaga ◽  
Yoshinori Itaya ◽  
Shigekatu Mori
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Coal Combustion ◽  
Radiative Heat ◽  
Heat Transfer Model ◽  
Pulverized Coal ◽  
Transfer Model ◽  
Pulverized Coal Combustion

CFD Modeling of Cogeneration Burner Applications and the Significance of Thermal Radiative Heat Transfer Effects

2003 ◽  
Author(s):  
A. F. Tenbusch
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Radiation ◽  
System Design ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Flow Distribution ◽  
Cfd Modeling ◽  
Large Temperature ◽  
Flow Heat

Industrial burners provide process heat for a wide range of applications including cogeneration power production. In such applications a (typically) natural gas fired stationary turbine powers an electric generator and indirectly powers a heat recover steam generator (HRSG). The HRSG steam cycle operates by reclaiming the residual thermal energy of the gas turbine exhaust (GTE) flow. Burners are used to reheat the GTE and increase plant capacity during peak demand periods. CFD modeling is used in the design of burner systems for HRSG applications. GTE flow exiting the turbine unit is passed through a diffuser and then expanded into ductwork where the steam system heat exchangers are located. The expansion of the GTE flow from the turbine diffuser to the full cross section of the ductwork is usually severe and creates an uneven flow distribution. Flow correcting structure may be needed to distribute the flow depending upon the severity of the duct expansion. CFD modeling is used to predict the flow distribution of the GTE and guide the design of any necessary flow correcting structure. Burners are typically installed in an array upstream of the application heat exchanger inlet. CFD combustion, heat transfer, and flow analysis is employed in the burner system design process to locate the burner array, determine any necessary flow baffling, and to ensure and provide a uniform thermal distribution at the downstream heat exchanger inlet. Excessive thermal variation in the GTE flow entering the heat exchanger results in large temperature gradients that can lead to thermal cracking and fatigue of the heat exchanger surfaces. CFD modeling is used to ensure that the burner system design produces a uniform flow and temperature distribution at the heat exchanger inlet region downstream of the burners. This report presents a case study of a CFD flow, heat-transfer, and combustion analysis for a typical HRSG burner application. Two CFD models were constructed for the analysis. The first model included the coupled effects of flow, heat transfer, and combustion for the entire HRSG model volume, but excluded the effects of thermal radiation. The second model included a sub-domain of the HRSG volume near the burner and included the additional effects of thermal radiation, both surface radiation and the effects of the radiatively participating flue gas. Radiative effects were included in the second model by employing the Discrete Transfer Method. Results of the study showed the significant role thermal radiative heat transfer had on the resulting temperature predictions downstream of the flame zone.

scholarly journals Conjugate Heat Transfer Characteristics in a Highly Thermally Loaded Film Cooling Configuration with TBC in Syngas

Aerospace ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 16
Author(s):  
Jing Ren ◽  
Xueying Li ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Transfer Model ◽  
Plate Temperature ◽  
Total Percentage ◽  
Barrier Coating

Future power equipment tends to take hydrogen or middle/low heat-value syngas as fuel for low emission. The heat transfer of a film-cooled turbine blade shall be influenced more by radiation. Its characteristic of conjugate heat transfer is studied experimentally and numerically in the paper by considering radiation heat transfer, multicomposition gas, and thermal barrier coating (TBC). The Weighted Sum of Gray Gases Spectral Model and the Discrete Transfer Model are utilized to solve the radiative heat transfer in the multicomposition field, while validated against the experimental data for the studied cases. It is shown that the plate temperature increases significantly when considering the radiation and the temperature gradient of the film-cooled plate becomes less significant. It is also shown that increasing percentage of steam in gas composition results in increased temperature on the film-cooled plate. The normalized temperature of the film-cooled plate decreases about 0.02, as the total percentage of steam in hot gas increases 7%. As for the TBC effect, it can smooth out the temperature distribution and insulate the heat to a greater extent when the radiative heat transfer becomes significant.

Effect of Non Uniform Flow Distribution on Single Phase Heat Transfer in Parallel Microchannels

2007 ◽  
Author(s):  
Akhilesh V. Bapat ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Single Phase ◽  
Flow Distribution ◽  
Uniform Flow ◽  
Hydrodynamic Performance ◽  
Flow Area ◽  
Cross Sectional ◽  
Uniform Flow Distribution ◽  
Parallel Microchannels

The continuum assumption has been widely accepted for single phase liquid flows in microchannels. There are however a number of publications which indicate considerable deviation in thermal and hydrodynamic performance during laminar flow in microchannels. In the present work, experiments have been performed on six parallel microchannels with varying cross-sectional dimensions. A careful assessment of friction factor and heat transfer in is carried out by properly accounting for flow area variations and the accompanying non-uniform flow distribution in individual channels. These factors seem to be responsible for the discrepancy in predicting friction factor and heat transfer using conventional theory.

Analysis of Radiative Heat Transfer Model for Pulverized Coal Combustion

2004 ◽  
Vol 2004 (0) ◽  
pp. 331-332
Author(s):  
Akinori GOTO ◽  
Hideto HAGIYA ◽  
Yoshio Morozumi ◽  
Hideyuki AOKI ◽  
Takatoshi MIURA
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Coal Combustion ◽  
Radiative Heat ◽  
Heat Transfer Model ◽  
Pulverized Coal ◽  
Transfer Model ◽  
Pulverized Coal Combustion
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