Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Specific Surface Area Measurement by Air Permeability with Consideration for the Molecular Flow Effect [Translated]†
Because gas permeation through a powder bed is affected by molecular flow, applicability of the Kozeny-Carman equation, which neglects this effect, is limited to powders coarser than about 10 μm. ΦB=ΦV + δΦM is a general expression in some permeability equations for finer powders, where ΦB denotes the permeability of a bed, ΦV is a viscous flow term, and ΦM is a molecular flow term. δ is a constant that adjusts for the molecular flow effect. It has been more than 40 years since δ=0.515 was proposed by Rigden, 0.97 by Lea and Nurse, and 1.215 by Carman. It is because of these large differences in δ that the Kozeny-Carman equation is still used. In this paper δ=0.82 is proposed as a reasonable value based on a least squares analysis of Rigden's data and with reference to Knudsen's equation of capillary permeation. The use of δ=0.82 allows the more reasonable measurement of powders down to about 1 μm. † This report was originally printed in J. Soc. Powder Technology, Japan. 35(9), 649-654 (1998) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
Specific Surface Area Measurement by Air Permeability with Consideration for the Molecular Flow Effect [Translated]†
Because gas permeation through a powder bed is affected by molecular flow, applicability of the Kozeny-Carman equation, which neglects this effect, is limited to powders coarser than about 10 μm. ΦB=ΦV + δΦM is a general expression in some permeability equations for finer powders, where ΦB denotes the permeability of a bed, ΦV is a viscous flow term, and ΦM is a molecular flow term. δ is a constant that adjusts for the molecular flow effect. It has been more than 40 years since δ=0.515 was proposed by Rigden, 0.97 by Lea and Nurse, and 1.215 by Carman. It is because of these large differences in δ that the Kozeny-Carman equation is still used. In this paper δ=0.82 is proposed as a reasonable value based on a least squares analysis of Rigden's data and with reference to Knudsen's equation of capillary permeation. The use of δ=0.82 allows the more reasonable measurement of powders down to about 1 μm. † This report was originally printed in J. Soc. Powder Technology, Japan. 35(9), 649-654 (1998) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
Specific Surface Area Measurement by Air Permeability with Consideration for the Molecular Flow Effect [Translated]†
Akira Suganuma (Autor:in) / Yu Matsumoto (Autor:in) / Egure Murata (Autor:in) / Toshitaka Hamada (Autor:in)
2014
Aufsatz (Zeitschrift)
Elektronische Ressource
Unbekannt
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