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Methodical selection of thermal conductivity models for porous silica-based media with variation of gas type and pressure

Sonnick, S. ORCID iD icon; Erlbeck, L.; Meier, M.; Nirschl, H.; Rädle, M.

Abstract:

If the effective thermal conductivity of a silica powder in any gas atmosphere is to be calculated analytically, one is faced with a whole series of decisions. There are a lot of different models for the gas thermal conductivity in the pores, the thermal accommodation coefficient or the effective thermal conductivity itself in the literature. Furthermore, it has to be decided which input parameters should be used. This paper gives an overview and recommendations as to which calculation methods are best suited for the material classes of precipitated silica, fumed silica, silica gel and glass spheres. All combinations of the described methods result in a total of 2800 calculation models which are compared with pressure-dependent thermal conductivity measurements of 15 powdery materials with 7 different gases using Matlab computations. The results show that with a model based on a spherical unit cell, which considers local Knudsen numbers, the measuring points of all powder-gas combinations can be determined best with an average variance of about 18.5%. If the material class is known beforehand, the result can be predicted with an average accuracy of about 10% with the correspondingly determined methods.


Verlagsausgabe §
DOI: 10.5445/IR/1000142378
Veröffentlicht am 27.01.2022
Originalveröffentlichung
DOI: 10.1016/j.ijheatmasstransfer.2022.122519
Scopus
Zitationen: 10
Web of Science
Zitationen: 8
Dimensions
Zitationen: 9
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Mechanische Verfahrenstechnik und Mechanik (MVM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 0017-9310, 1879-2189
KITopen-ID: 1000142378
Erschienen in International Journal of Heat and Mass Transfer
Verlag Elsevier
Band 187
Seiten Art.-Nr.: 122519
Nachgewiesen in Dimensions
Scopus
Web of Science
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