Void fraction predictive method based on the minimum kinetic energy

Abstract

List of symbols Variables A Area, m 2 c i Constant and exponent, non-dimensional C 0 Distribution parameter, non-dimensional d Diameter, m dA Cross-sectional area element, m 2 g Gravitational acceleration, m/s 2 G Mass velocity, kg/m 2 s j Superficial velocity, m/s K Momentum coefficient, non-dimensional T Temperature, °C u In situ velocity, m/s u gj Drift parameter, m/s V z Axial component of velocity, m/s x Vapor quality, non-dimensional Dimensionless parameters Fr Froude number We Weber number X tt Martinelli parameter Greek letters α Void fraction, non-dimensional β Volumetric gas fraction, non-dimensional ε Mean absolute deviation, non-dimensional γ 10 Fraction of data predicted within ± 10 % λ Capillary length, m μ Dynamic viscosity, kg/m s ρ Density, kg/m 3 σ Surface tension, N/m θ Inclination relative to horizontal plane, degrees ξ Shedd [21] parameter, non-dimensional

Overview of Void Fraction Measurement Techniques, Databases and Correlations for Two-Phase Flow in Small Diameter Channels

“…Note that the best results occur in regions of high void fractions. In terms of λ 10% , the best predictions were provided by Tibiriçá et al [2], followed by Kanizawa et al [79], Woldesemayat and Ghajar [5], Xu and Fang [8], the new correlation and Chisholm [71]. Figure 8.…”

“…Using the microchannel database, the best correlations according to were the new correlation, Xu and Fang [8], Rouhani and Axelsson [68], Woldesemayat and Ghajar [5], Chisholm [71] and Tibiri¸c´a et al [1]. In terms of λ 10% , the best predictions were given by Tibiri¸c´a et al [1], followed by the new proposed correlation, Woldesemayat and Ghajar [5], Xu and Fang [8], Kanizawa et al [79] and Cioncolini and Thome [6].…”

“…For the macrochannel database (Table 4), the best correlations according to were provided by Tibiri¸c'a et al [2], Woldesemayat and Ghajar [5], Kanizawa et al [79], the new correlation, Graham [75] and Chisholm [71]. In terms of λ 10% , they were Kanizawa et al [79], Tibiri¸c'a et al [1], Woldesemayat and Ghajar [5], Chisholm [71], Xu and Fang [8] and Graham [75].…”

“…The database was obtained for R11, R12, R22, R134a and R410a in ducts with 0.5 to 10 mm in diameter. Kanizawa and Ribatski [79] developed a miscellaneous type correlation based on the principle of minimum kinetic energy. The database was obtained for R134a, R235fa and R600a in horizontal and vertical tubes with 0.508 to 50.8 mm in diameter.…”

Pressure and shear stress analysis in a normal triangular tube bundle based on experimental flow velocity field

“…This fact highlights the importance of studies focused on external flows across tube bundles. However, as pointed out by Kanizawa and Ribatski [1,2], the number of publications focused on external flows across tube bundles is considerably lower than those focused on internal flows mainly because of the geometric complexity of these devices. Paul et al [3] indicate that most of the studies performed for external flows across tube bundles are focused on global parameters such as volumetric void fractions and total pressure drop.…”