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- Lundström, Staffan, et al.
(författare)
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Measurement of the permeability tensor of compressed fibre beds
- 2002
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Ingår i: Transport in Porous Media. - 0169-3913 .- 1573-1634. ; 47:3, s. 363-380
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Tidskriftsartikel (refereegranskat)abstract
- A new method to measure the permeability tensor of highly compressed fibre beds is developed. The method is based on saturated parallel flow and is evaluated through experiments with various textile materials: press fabrics used in papermaking and fibre reinforcements designed for composites. Since the materials are in the form of sheets, two measuring cells are used, one for the principal in-plane permeabilities and the other for the out-of-plane permeability. A unique feature is that the edge and the bulk flow are measured separately, so that any influence from enhanced or suppressed edge flow may be eliminated. The technique is evaluated with good results in terms of scatter in the measured permeability and the influence of test geometry, pressure, and liquid properties.
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| 2. |
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| 3. |
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| 4. |
- Hager, Jörgen, et al.
(författare)
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The thermodynamic significance of the local volume averaged temperature
- 2002
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Ingår i: Transport in Porous Media. - 0169-3913. ; 46:1, s. 19-35
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Tidskriftsartikel (refereegranskat)abstract
- Since the temperature is not an additive function, the traditional thermodynamic point of view suggests that the volume integral of the temperature has no precise physical meaning. This observation conflicts with the customary analysis of non-isothermal catalytic reactors, heat pipes, driers, geothermal processes, etc., in which the volume averaged temperature plays a crucial role. In this paper we identify the thermodynamic significance of the volume averaged temperature in terms of a simple two-phase heat transfer process. Given the internal energy as a function of the point temperature and the density e(beta) = F (T-beta, rho(beta)), we show that the volume averaged internal energy is represented by [e(beta)](beta) = F([T-beta](beta), [rho(beta)](beta)), when e(beta) is a linear function of T-beta and rho(beta), or when the traditional length-scale constraints associated with the method of volume averaging are satisfied. When these conditions are not met, higher order terms involving the temperature gradient and the density gradient appear in the representation for [e(beta)](beta).
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