Proper Modeling of Radiative Heat Transfer in Clear Glass Melts

Lankhorst, Adriaan; Thielen, L.; Simons, P.J.P.M.; Habraken, Andries

doi:10.1002/9781118710838.ch19

Cited by 7 publications

(4 citation statements)

References 4 publications

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“…This model only needs room temperature chemical compositional data as input, including total Fe 2 O 3 content, total Cr 2 O 3 content, SO 3 content and the glass redox state, expressed as Fe 2+ /Fe tot ratio at room temperature. The model combines temperature-dependent redox calculations using the Gibbs redox tool within Celsian's CFD model GTM-X 5,6 and a semi-empirical model for the temperature-dependent changes in optical absorption of Fe-, Cr ions and the silicate glass matrix, derived from the high temperature spectral measuring data. In other words, in this new predictive model the effects of temperature-dependent changes in the redox state of a glass melt on the Rosseland heat radiation parameters are separated from the effects of structural (ie ligand field) changes at melting temperatures and from glass matrix spectral features.…”

Section: Introductionmentioning

confidence: 99%

Characterization of high temperature optical spectra of glass melts and modeling of thermal radiation conductivity

Faber

Rongen²,

Lankhorst³

et al. 2020

Int J of Appl Glass Sci

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Two innovative experimental techniques for measuring the high temperature near infrared optical spectra of glass melts are compared. The critical experimental features of both techniques, one based on transmission and the other based on emittance measurements, are reviewed. Typical results of both techniques, including high temperature spectra and values for the Rosseland mean absorption coefficient and thermal radiation conductivity versus temperature for similar glass melts, are compared. The study is focused on sulfate fined soda lime silicate glass melts colored with iron oxide and chromium oxide and on the effect of the glass redox state on the thermal radiation conductivity. It is shown that essentially different measuring principles provide consistent results for similar glass melt types, that is, colors. Using the high temperature spectra of a large variety of (colored) glasses, a new semi-empirical model is developed for predicting the Rosseland radiation conductivity of arbitrary sulfate fined soda lime silicate glass melts, colored with iron oxide and chromium oxide. By separating the effects of (a) the temperature-dependent redox state, (b) the high temperature changes in ligand field strengths and (c) the glass matrix, the model reliably predicts the Rosseland radiation conductivity, with a chemical analysis of the glass as input only. K E Y W O R D Scolor< optical properties, glass forming melts< properties, thermal conductivity< glass forming melts

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Section: Introductionmentioning

confidence: 99%

Characterization of high temperature optical spectra of glass melts and modeling of thermal radiation conductivity

Faber

Rongen²,

Lankhorst³

et al. 2020

Int J of Appl Glass Sci

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“…The simulations were carried out using CelSian's multi‐physics glass furnace CFD model, GTM‐X. The model is described in detail in References . Here we will describe and discuss only on the results for the glass melt.…”

Section: Modeling Of Flow and Heat Transfer In A Meltermentioning

confidence: 99%

“…The model is described in detail in References. 16,17 Here we will describe and discuss only on the results for the glass melt. Figure 6 shows the schematic of the float glass furnace modeled.…”

Section: Modeling Of Flow and Heat Transfer In A Meltermentioning

confidence: 99%

Radiative heat transfer in processing of glass‐forming melts

Choudhary

Purnode

Lankhorst³

et al. 2017

Int J of Appl Glass Sci

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The paper summarizes the findings of a study on mathematical modeling of heat transfer in glass melts using the commonly employed diffusion or Rosseland approximation (R) for optically thick media and the more general, spectral discrete ordinates (DO) approach. The systems considered were the melting of an ultra‐clear glass in a furnace (optical thickness ~ 10) and heat transfer in 2 glass melts with different levels of iron oxide flowing through a delivery channel (optical thicknesses of ~17 and ~80). The results showed that the use of the R approach for modeling heat transfer in the ultra‐clear glass will lead to serious errors in the prediction of important practical parameters such as the refractory temperature, energy efficiency, and the quality of glass melt. The results for the channels showed that differences between the 2 thermal radiation models began to narrow as the optical thickness value approached 17. The paper also presents brief reviews of high‐temperature absorption spectra of commercial glass melts and the theoretical background on thermal radiation in participating media. In addition, a relatively simple system involving 1‐dimensional radiation heat transfer in a participating medium is used to illustrate the implications of using the diffusion approximation.

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“…In this part, a demonstration furnace [3] is selected and parameter studies are discussed that investigate glass product quality for those cases where the main glass flow patterns are changed. The chosen furnace configuration is an oxyfuel fired float furnace (Figure 4 The main characteristics of the furnace are summarized in Table 1.…”

Section: Demonstration Casementioning

confidence: 99%

Glass Melt Quality Optimization by CFD Simulations and Laboratory Experiments

Habraken¹,

Lankhorst²,

Verheijen³

et al. 2016

76th Conference on Glass Problems

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The quality of a glass melting process is determined by the melting in performance, the sand grain dissolution and the removal of gas bubbles by fining. For good quality it is essential that each trajectory/path starting from batch charging to the throat or waist of the tank shows complete melting and fining. Each part of the glass melt should be exposed to temperatures such that fining can occur. The fining onset temperature and melting performance for an industrial glass tank depends on the batch composition, sand grain size, type and amount of fining agent, furnace atmosphere and the redox number of the batch. Laboratory experiments are carried out to determine the most important parameters for industrial batches. The results of these laboratory experiments are used as input to the CFD (Computational Fluid Dynamics) model GTM X, which then provides the temperature and flow fields in the industrial melting tank, along with the calculation of the individual glass melt trajectories. This combination of experiments and CFD simulation proves to be a very powerful tool for determining the fining and melting performance of industrial furnaces. Special attention will be paid to the location of the fining zone, with respect to the convection flows in the melt.

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Proper Modeling of Radiative Heat Transfer in Clear Glass Melts

Cited by 7 publications

References 4 publications

Characterization of high temperature optical spectra of glass melts and modeling of thermal radiation conductivity

Characterization of high temperature optical spectra of glass melts and modeling of thermal radiation conductivity

Radiative heat transfer in processing of glass‐forming melts

Glass Melt Quality Optimization by CFD Simulations and Laboratory Experiments

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