Investigation on thermal radiation spectra of coal ash deposits

Saljnikov, Aleksandar; Komatina, Mirko; Manović, Vasilije; Gojak, Milan; Goričanec, Darko

doi:10.1016/j.ijheatmasstransfer.2008.12.007

Cited by 13 publications

(8 citation statements)

References 9 publications

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“…The model given in Sec. The results show that the ash deposit spectral emissivities increase with increasing temperature which agrees with previous results [8,9,11,12]. However, due to the lack of temperature-2.0 Fig.…”

Section: Effects Of Temperaturesupporting

confidence: 91%

“…2 for two ash deposit samples. The results are not compared with other experimental data [8][9][10][11][12] due to the lack of sufficient information conceming the ash deposits. The results are not compared with other experimental data [8][9][10][11][12] due to the lack of sufficient information conceming the ash deposits.…”

Section: Effects Of Mierostructurementioning

confidence: 99%

“…Since the ash deposit microstructures change with temperature and the microstructure significantly affects the spectral emissivity [2,8,9], the effects of temperature on the ash deposit spectral emissivities are actually attributed to the accordingly changed ash deposit microstructure. The model given in Sec.…”

Section: Effects Of Temperaturementioning

confidence: 99%

“…Saljnikov et al [8,9] measured temperature dependent total and spectral emissivities for four kinds of ash deposits for temperatures from 560 to 1460 K. Moore et al [10] measured in situ spectral emissivities of ash deposits formed by burning bituminous and sub-bituminous coals. Saljnikov et al [8,9] measured temperature dependent total and spectral emissivities for four kinds of ash deposits for temperatures from 560 to 1460 K. Moore et al [10] measured in situ spectral emissivities of ash deposits formed by burning bituminous and sub-bituminous coals.…”

Section: Introductionmentioning

confidence: 99%

“…Saljnikov et al [8] and Shimogori et al [14] developed empirical correlations for ash deposit spectral emissivities. Saljnikov et al [8] and Shimogori et al [14] developed empirical correlations for ash deposit spectral emissivities.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits

Liu

Duan

Yang

et al. 2014

Journal of Heat Transfer

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Coal ash inevitably forms deposits as combustion residue on the walls and heat transfer surfaces of coal-fired boilers. Ash deposits decrease the boiler efficiency, reduce the generating capacity, and cause unscheduled outages. The radiative heat transfer is the major heat transfer mechanism in utility boilers: thus, the ash deposit emissivity is critical to boiler efficiency and safety. This paper presents a radiative transfer model to predict the spectral emissivities of coal ash deposits. The model includes the effects of the microstructure, chemical composition, and temperature. Typical ash deposit microstructures are generated using diffusion-limited aggregation (DLA). The radiative properties are then calculated using the generalized multiparticle Mie-solution (GMM). The combined GMM and DLA model predicts spectral emissivity better than the original Mie theory and Tien's dependent scattering theory with the average relative difference between predicted results and experimental data decreasing from 17.8% to 9.1% for sample 1 and from 18.6% to 4.2% for sample 2. Maxwell-Garnett (MG) effective medium theory is used to calculate the ash deposit optical constants based on the chemical compositions to include the effect of chemical composition. Increasing temperatures increase the particle diameters and particle volume fractions and, thus, the spectral emissivities. The spectral emissivity ultimately remains constant and less than one. The homogeneous slab model gives the upper limit of the ash deposit spectral emissivity.

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Section: Effects Of Temperaturesupporting

confidence: 91%