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131.
S. W. Peng 《Heat and Mass Transfer》1994,29(8):501-505
Present paper presents a derivation of Luikov equations applicable to sublimation-drying. The physical situation and transfer mechanism are elucidated clearly. The coefficients appearing in Luikov equations are given in a more explicit way. Some formulation mistakes in recent publications are indicated.
Nomenclature C M v/V f, concentration of vapor, kg/m3 - c pv specific heat of vapor at constant pressure, J/kg K - c pw specific heat of adsorbed water at constant pressure, J/kg K - c s specific heat of solid skeleton, J/kg K - C s M s/V f, concentration of solid skeleton, kg/m3 - C w M w/V f, concentration of adsorbed water, kg/m3 - f V w/V f, volumetric fraction of adsorbed water - j F mass flux of vapor by diffusion (Fick) transfer, kg/m2 s - j D mass flux of vapor by filtration (Darcy) transfer, kg/m2 s - j v total mass flux of vapor, kg/m2 s - k permeability, m2 - M s mass of solid skeleton, kg - M v mass of vapor in pores, kg - M w mass of adsorbed water, kg - P pressure, Pa - q heat flux, W/m2 - R gas constant, J/kg K - T temperature, K - V f volume of the framework of porous medium, m3 - V v volume of vapor in porous medium, m3 - V w volume of the absorbed water, m3 Greek symbols /(c p), effective thermal diffusivity, m2/s - m effective vapor diffusivity in porous medium, m2/s - p R T /, Luikov pressure diffusivity, m2/s - +f, porosity of the porous medium - effective thermal conductivity of porous body, W/m K - dynamic viscosity of vapor, kg/m s - kinematic viscosity, m2/s - Ck/=k/, Luikov filtration motion coefficient, s - V v/V f, volumetric fraction of vapor - density of absorbed water, kg/m3 - (c p) M v c pv+M s c s+M w c pw /V f=Cc pv+C s c s+fc pw, effective product of density and specific heat of humid porous body, J/m3K 相似文献
Anwendung der Luikov-Gleichungen auf die Sublimationstrocknung
Zusammenfassung Die Untersuchung bezieht sich auf eine Ableitung der Luikov-Gleichungen, mittels deren sich der Vorgang der Sublimationstrocknung analysieren läßt. Physikalische Anfangssituation und Austauschmechanismen werden klar herausgestellt und die in den Luikov-Gleichungen auftretenden Koeffizienten in expliziter Weise angegeben. Ferner erfolgt Hinweis auf Formulierungsfehler in jüngeren Veröffentlichungen.
Nomenclature C M v/V f, concentration of vapor, kg/m3 - c pv specific heat of vapor at constant pressure, J/kg K - c pw specific heat of adsorbed water at constant pressure, J/kg K - c s specific heat of solid skeleton, J/kg K - C s M s/V f, concentration of solid skeleton, kg/m3 - C w M w/V f, concentration of adsorbed water, kg/m3 - f V w/V f, volumetric fraction of adsorbed water - j F mass flux of vapor by diffusion (Fick) transfer, kg/m2 s - j D mass flux of vapor by filtration (Darcy) transfer, kg/m2 s - j v total mass flux of vapor, kg/m2 s - k permeability, m2 - M s mass of solid skeleton, kg - M v mass of vapor in pores, kg - M w mass of adsorbed water, kg - P pressure, Pa - q heat flux, W/m2 - R gas constant, J/kg K - T temperature, K - V f volume of the framework of porous medium, m3 - V v volume of vapor in porous medium, m3 - V w volume of the absorbed water, m3 Greek symbols /(c p), effective thermal diffusivity, m2/s - m effective vapor diffusivity in porous medium, m2/s - p R T /, Luikov pressure diffusivity, m2/s - +f, porosity of the porous medium - effective thermal conductivity of porous body, W/m K - dynamic viscosity of vapor, kg/m s - kinematic viscosity, m2/s - Ck/=k/, Luikov filtration motion coefficient, s - V v/V f, volumetric fraction of vapor - density of absorbed water, kg/m3 - (c p) M v c pv+M s c s+M w c pw /V f=Cc pv+C s c s+fc pw, effective product of density and specific heat of humid porous body, J/m3K 相似文献
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135.
Jürgen Jost Xiaowei Peng Guofang Wang 《Calculus of Variations and Partial Differential Equations》1996,4(3):205-218
The Seiberg-Witten equations that have recently found important applications for four-dimensional geometry are the Euler-Lagrange equations for a functional involving a connection A on a line bundleL and a section of another bundleW
+ constructed fromL and a spinor bundle on a given four-dimensional Riemannian manifold. We show the regularity of weak solutions and the Palais-Smale condition for this functional. 相似文献
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Parametric normalization for full-energy peak count rates obtained at different geometries 总被引:1,自引:0,他引:1
Tian Weizhi Ni Bangfa Wang Pingsheng Peng Lixin 《Journal of Radioanalytical and Nuclear Chemistry》1993,170(1):27-42
The Effective Interaction Depth (EID) law has been systematically studied and applied to parametric normalization for peak count rates obtained at different source-detector distances (S-D). The errors caused by EID normalization are less than 4% over the full range of S-D (from to several mm) for true coincidence-free -rays. Parametric corrections for the true coincidence (summing) effect are also established, based on simplified decay schemes and P/T ratio determinations. The total response of Ge detector for single-energy -rays (T) is clearly defined with scattering contributions from surroundings included. Errors from summing effect corrections are also less than 4%. The combined EID normalization and summing effect corrections give an error no greater than 5.7% for the worst situations (several mm S-D and cascade-crossover decay scheme), acceptable for most practical K0 NAA. 相似文献
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