Improved Spectral Absorption Coefficient Grouping Strategies in Radiation Heat Transfer Calculations for H2O–CO2-Soot Mixtures

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Yue Zhou ◽  
Qiang Wang ◽  
Haiyang Hu
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Molar Ratio ◽  
Spectral Absorption ◽  
Radiation Heat ◽  
Distribution Models ◽  
Full Spectrum ◽  
Work Strategies ◽  
Grouping Strategies ◽  
Significant Temperature

In the present work, strategies for the grouping of the spectral absorption coefficients used in multiscale (MS) multigroup (MG) full-spectrum k-distribution models were improved by considering the effects of variations in both temperature and species molar ratio on the correlated-k characteristics of the spectra of H2O–CO2-soot mixtures. The improvements in the accuracy of predictions of radiation heat transfer characteristics resulting from these new grouping strategies were evaluated using a series of semi-one-dimensional (1D) cases with significant temperature, participating species molar ratio, and pressure inhomogeneities. Finally, evaluations of grouping strategies were presented on calculation of the full-spectrum thermal images of an actual aeroengine combustor.

Improved MSMGFSK Models Apply to Gas Radiation Heat Transfer Calculation of Exhaust System of TBCC

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Haiyang Hu ◽  
Qiang Wang
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Thermal Emission ◽  
Radiation Heat Transfer ◽  
Exhaust System ◽  
Combined Cycle ◽  
Large Temperature ◽  
Radiation Heat ◽  
Full Spectrum ◽  
Radiation Emission

The multiscale multigroup full-spectrum k-distribution (MSMGFSK) model was improved to adapt to radiation heat transfer calculations of combustion gas flow field with large temperature and pressure gradient. The improvements in calculation accuracy resulting from new sorting strategy of the spectral absorption coefficients were validated using a series of semi-1D problem in which strong temperature, pressure, and mole fraction inhomogeneities were present. A simpler method to attain compatibility between the MSMGFSK model and the gray-wall radiation emission has been established and validated. Finally, estimates are given for the calculation of wall radiation heat transfer characteristics and thermal emission imaging of the exhaust system of the parallel turbine-based combined cycle (TBCC) engine, using finite volume method (FVM) and ray trace method (RT), respectively.

Effect of Bituminous Coal Properties on Heat Transfer Characteristic in the Boiler Furnaces

2004 ◽  
Author(s):  
B. Chudnovsky ◽  
A. Talanker
Keyword(s):  
Heat Transfer ◽  
Bituminous Coal ◽  
Radiation Heat Transfer ◽  
Combustion Process ◽  
Heat Fluxes ◽  
Al2o3 Content ◽  
Molar Ratio ◽  
Operational Experience ◽  
Radiation Heat ◽  
Transfer Properties

Over the past years experience has been gained in employing changing types of imported coal. Apart from the proximate analysis this led to development of evaluation criteria regarding the operation of coals. These are criteria numbers obtained from operational experience and criteria numbers used for the characterization of specific operational properties on the basis of special laboratory analyses. The study evaluates the effect of the characteristics of pulverized coal on the furnace fouling and radiation heat transfer. The aim of the study was to access whether fouling and radiation heat transfer could be predicted from coal characteristics. The paper presents the experimental results on the fouling propensity of fifteen coals tested in a 575 MW combustion engineering tangential firing boiler. The results showed that no coals produced a strong molten deposit. In order to rank the fouling propensity and radiation heat transfer properties numerically, we measured the profile of incident heat fluxes, defined furnace exit flue gas temperature and absorbed heat fluxes. The basic molar ratio correlates the fouling propensity. Besides that increasing of SiO2 and Al2O3 content in the ash strongly reduces water wall absorptivity factor. The present work is also concerned with the effect of different bituminous coal on their flame emissivity. Using the radiation properties of flue gases derived from the full scale experiments, we run computational fluid dynamics (CFD) on the combustion process. The known fouling and radiation heat transfer properties enable the prediction of the effect of coal quality on the performance of a specific boiler.

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