The Experts below are selected from a list of 492 Experts worldwide ranked by ideXlab platform
Manoj K. Choudhary - One of the best experts on this subject based on the ideXlab platform.
-
Mathematical Modeling of Flow and Heat-Transfer Phenomena in Glass Furnace Channels and Forehearths
Journal of the American Ceramic Society, 1991Co-Authors: Manoj K. ChoudharyAbstract:A three-dimensional mathematical model was developed to calculate fluid-flow and heat-transfer phenomena in a channel/Forehearth system used for delivering glass from the melting end to the forming end of a continuous-glass-fiber furnace. The model allowed for a varying cross section of the delivery system and for the temperature-dependent physical properties of the molten glass. Also, a formulation was presented to calculate heat transfer by radiation at the combustion gas/glass interface. The model was used to investigate the effects of natural convection, throughput, and radiation in the glass on velocity and temperature distribution in a glass delivery system. The results showed that, although the natural convection velocities were much lower than the average velocity due to throughput, the presence of natural convection significantly affected the flow path lines in the system. The results also illustrated the distribution of surface and bottom glass streams entering a channel into different Forehearths.
J. Srinivasan - One of the best experts on this subject based on the ideXlab platform.
-
Effect of wall emissivities on radiation heat transfer in glass tank Forehearths
Heat and Mass Transfer, 1995Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:In an earlier work, we had proposed a two-band, non-grey radiative transfer model for heat transfer in Forehearths with simultaneous optically thick and thin approximations for molten glass interiors and at boundaries. Here using the same model, the radiative interaction of the top-crown and bottom-refractory walls with interior layers of shallow molten glass is studied by varying the wall emissivities. The Forehearth exit temperature profiles for higher wall emissivities (0.9) show better conditioning of the glass for white flint glasses (optically thin).
-
Effect of wall emissivities on radiation heat transfer in glass tank Forehearths
Heat and Mass Transfer, 1995Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:In einer früheren Arbeit wurde ein Zweibanden-Modell für den nichtgrauen Strahlungs-Wärmeübergang in Vorherden entwickelt, das auf Näherungen für sowohl optisch dicke wie dünne Medien bezüglich des Strahlungsaustausches zwischen Glasschmelze und Grenzflächen basierte. Unter Verwendung des gleichen Modells wird jetzt der Strahlungsaustausch zwischen Herddecke und-boden mit dazwischen liegender, dünner Glasschmelzeschicht untersucht, wobei die Emissionsverhältnisse der Begrenzungswände variiert werden. Die Vorherd-Austrittstemperaturprofile zeigen, daß sich bei hohen Wandemissivitäten (0,9) eine bessere Temperierung (optisch dünnen) Flintglases erzielen läßt. In an earlier work, we had proposed a two-band, nongrey radiative transfer model for heat transfer in Forehearths with simultaneous optically thick and thin approximations for molten glass interiors and at boundaries. Here using the same model, the radiative interaction of the top-crown and bottomrefratory walls with interior layers of shallow molton glass is studied by varying the wall emissivities. The Forehearth exit temperature profiles for higher wall emissivities (0.9) show better conditioning of the glass for white flint glasses (optically thin).
-
The modelling of radiation heat transfer in Forehearths units in glass melting
Heat and Mass Transfer, 1994Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:Die Wechselwirkung zwischen den Wärmetransportmoden Leitung, Konvektion und Strahlung in geschmolzenem Glas wurde für den speziellen Anwendungsfall des Vorherdes eines Glasschmelzofens untersucht. Es zeigte sich, daß bei flachen Glasschmelzflüssen, wie sie für Vorherde typisch sind, das zur Modellierung des Strahlungsaustauschprozesses häufig verwendete Strahlungs-Leitfähigkeitsmodell ungeeignet ist. Dies gilt insbesondere für farblose Gläser, welche unterhalb 2,8 μm nicht als optisch dick angesehen werden können. In der vorliegenden Arbeit wurde der Strahlungsaustausch in Glasschmelzen unter Berücksichtigung der Grenzfälle optisch „dick” und „dünn” auf strengere Weise behandelt. Auch der Strahlungsaustausch an den Grenzflächen fand realistischere Berücksichtigung. Im Falle farbloser Gläser zeigen die mit der geschilderten Methode erhaltenen Ergebnisse, daß der unmittelbare Strahlungsaustausch zwischen Schichten im Inneren der Glasschmelze und den Decken- und Bodenwänden des Ofens bzw. des Tiegels betrachtet werden muß. Die Profile der Vorherdaustrittstemperatur, berechnet nach der genaueren Methode, unterscheiden sich ganz wesentlich von jenen mit dem groben Modell ermittelten. The interaction between conduction, convection and radiation heat transfer in molten glass has been studied with specific reference to the Forehearth units of a glass tank furnace. In shallow molten glass flows as typically encountered in Forehearth units, the radiation-conductivity approach for modelling the radiative transfer process is found inappropriate. This is especially so for colourless glasses which are not optically thick below 2.8 microns. In the present work radiative heat transfer process in molten glass has been treated more rigourously by incorporating both optically thick and thin limits. The radiative interaction at the boundaries is treated more realistically. In the case of colourless glasses, the results obtained by the present method show the necessacity to account for the direct radiative interaction between the interior layers of the glass and refractory walls at the top and the bottom. The Forehearth exit temperature profiles obtained by using the present method are quite different with those obtained using the radiation conductivity approach.
J. Mcminn - One of the best experts on this subject based on the ideXlab platform.
-
The Emhart Glass 240 Forehearth
International glass journal, 2001Co-Authors: J. McminnAbstract:Forehearths have evolved from little more than gathering bay stubs to become mass glass conditioning systems some of which are capable of processing hundreds of tons of glass per day. Indeed, with some Forehearths being designed for tonnages of up to 300 tons per day, modern Forehearths can now accommodate tonnages greater than the daily tonnage of many of the furnaces in operation 20 years ago. Has this evolution forgotten the needs of the low tonnage producer? This article deals with their needs and presents them with the Emhart Glass answer.
-
More recent refractory design to improve Forehearth performance
International glass journal, 1999Co-Authors: J. McminnAbstract:The efficiency of Forehearths has been limited because of a lack of understanding of the interaction between the heating and cooling components within the Forehearth. PSR has developed a system which has greatly enhanced the cooling capability of direct air cooled Forehearths leading to increases in flexibility and greater glass homogeneity.
-
Glass conditioning : what is it and how do we achieve it ?
The Glass industry, 1999Co-Authors: J. McminnAbstract:Optimizing the combustion and cooling systems are the keys to Forehearth design philosophy.
-
Sensor system advances gob weight control
1999Co-Authors: J. McminnAbstract:Whilst developments in forming technology have advanced rapidly in recent years, improvements in Forehearth technology have been slower. The feeder mechanism affects gob weight stability and so to solve this problem, a sensing system has been developed that can achieve significant advances in the control of the forming process.
-
Changing the rules on Forehearth dimensions
1997Co-Authors: J. McminnAbstract:Optimisation of the cooling configurations in the PSR System 500 Forehearth has dramatically increased the level of control available to its operators. The improved performance of these conditioning systems has also made some of the traditional assumptions about the necessary size of Forehearths inappropriate.
R. Sims - One of the best experts on this subject based on the ideXlab platform.
-
Gas heating systems for working ends and Forehearths
2000Co-Authors: R. SimsAbstract:A reliable and efficient heating system for working ends and Forehearths is an important factor in the achievement of stable and economic production, and as quality requirements for the final products climb, so the importance of the heating system increases.
-
Third generation Forehearth offers flexible approach
1999Co-Authors: R. SimsAbstract:Tests have been carried out by SORG on one Forehearth to establish whether further improvements could be made to the thermal homogeneity. The results of the trials are discussed in this article.
-
Improving the equalising section
International glass journal, 1997Co-Authors: R. SimsAbstract:On many Forehearths the so-called equalising section is expected to reduce temperature differences in the glass to an acceptable level for the production. However in most cases we have little influence over what is happening. In addition, the residence time of the glass in this section has often become so short that little positive effect can be expected. The use of a high capacity radiation cooling system in the working end allows to complete the glass cooling as early as possible, thus leaving as much of the Forehearth as possible available for the equalising process. When the needed modification of the working end cannot be carried out, the application of a small electrical heating system in the equalising section can often provide a significant improvement.
-
Forehearth developments in container production
Glass international, 1995Co-Authors: R. SimsAbstract:The continually changing requirements of high capacity glass container manufacture have led to significant changes to the detailed engineering of PRECON working ends and AMC Forehearths since the concepts were first introduced in 1986. We describe how major innovations made in the application of the radiation cooling system have resulted in the concentration of the cooling process in the working end and if necessary the first Forehearth zone
-
Central process control for German container plant
1995Co-Authors: R. SimsAbstract:The need to obtain closer control of all aspects of the glass manufacturing process, coupled with the drive to rationalise the process monitoring functions, has led to the widespread application of centralised computer control system in the industry. We describe a system for the batch house, melting furnace, working end and Forehearths, plus the factory cullet return system, recently installed at DNL Behalterglas GmbH in Drebkau, Germany
Ap Roychowdhury - One of the best experts on this subject based on the ideXlab platform.
-
Effect of wall emissivities on radiation heat transfer in glass tank Forehearths
Heat and Mass Transfer, 1995Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:In an earlier work, we had proposed a two-band, non-grey radiative transfer model for heat transfer in Forehearths with simultaneous optically thick and thin approximations for molten glass interiors and at boundaries. Here using the same model, the radiative interaction of the top-crown and bottom-refractory walls with interior layers of shallow molten glass is studied by varying the wall emissivities. The Forehearth exit temperature profiles for higher wall emissivities (0.9) show better conditioning of the glass for white flint glasses (optically thin).
-
Effect of wall emissivities on radiation heat transfer in glass tank Forehearths
Heat and Mass Transfer, 1995Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:In einer früheren Arbeit wurde ein Zweibanden-Modell für den nichtgrauen Strahlungs-Wärmeübergang in Vorherden entwickelt, das auf Näherungen für sowohl optisch dicke wie dünne Medien bezüglich des Strahlungsaustausches zwischen Glasschmelze und Grenzflächen basierte. Unter Verwendung des gleichen Modells wird jetzt der Strahlungsaustausch zwischen Herddecke und-boden mit dazwischen liegender, dünner Glasschmelzeschicht untersucht, wobei die Emissionsverhältnisse der Begrenzungswände variiert werden. Die Vorherd-Austrittstemperaturprofile zeigen, daß sich bei hohen Wandemissivitäten (0,9) eine bessere Temperierung (optisch dünnen) Flintglases erzielen läßt. In an earlier work, we had proposed a two-band, nongrey radiative transfer model for heat transfer in Forehearths with simultaneous optically thick and thin approximations for molten glass interiors and at boundaries. Here using the same model, the radiative interaction of the top-crown and bottomrefratory walls with interior layers of shallow molton glass is studied by varying the wall emissivities. The Forehearth exit temperature profiles for higher wall emissivities (0.9) show better conditioning of the glass for white flint glasses (optically thin).
-
The modelling of radiation heat transfer in Forehearths units in glass melting
Heat and Mass Transfer, 1994Co-Authors: Ap Roychowdhury, J. SrinivasanAbstract:Die Wechselwirkung zwischen den Wärmetransportmoden Leitung, Konvektion und Strahlung in geschmolzenem Glas wurde für den speziellen Anwendungsfall des Vorherdes eines Glasschmelzofens untersucht. Es zeigte sich, daß bei flachen Glasschmelzflüssen, wie sie für Vorherde typisch sind, das zur Modellierung des Strahlungsaustauschprozesses häufig verwendete Strahlungs-Leitfähigkeitsmodell ungeeignet ist. Dies gilt insbesondere für farblose Gläser, welche unterhalb 2,8 μm nicht als optisch dick angesehen werden können. In der vorliegenden Arbeit wurde der Strahlungsaustausch in Glasschmelzen unter Berücksichtigung der Grenzfälle optisch „dick” und „dünn” auf strengere Weise behandelt. Auch der Strahlungsaustausch an den Grenzflächen fand realistischere Berücksichtigung. Im Falle farbloser Gläser zeigen die mit der geschilderten Methode erhaltenen Ergebnisse, daß der unmittelbare Strahlungsaustausch zwischen Schichten im Inneren der Glasschmelze und den Decken- und Bodenwänden des Ofens bzw. des Tiegels betrachtet werden muß. Die Profile der Vorherdaustrittstemperatur, berechnet nach der genaueren Methode, unterscheiden sich ganz wesentlich von jenen mit dem groben Modell ermittelten. The interaction between conduction, convection and radiation heat transfer in molten glass has been studied with specific reference to the Forehearth units of a glass tank furnace. In shallow molten glass flows as typically encountered in Forehearth units, the radiation-conductivity approach for modelling the radiative transfer process is found inappropriate. This is especially so for colourless glasses which are not optically thick below 2.8 microns. In the present work radiative heat transfer process in molten glass has been treated more rigourously by incorporating both optically thick and thin limits. The radiative interaction at the boundaries is treated more realistically. In the case of colourless glasses, the results obtained by the present method show the necessacity to account for the direct radiative interaction between the interior layers of the glass and refractory walls at the top and the bottom. The Forehearth exit temperature profiles obtained by using the present method are quite different with those obtained using the radiation conductivity approach.