Counter-current flow limitation in vertical pipes and a pressurizer surge line

In our serial studies, we derived Wallis type correlations for counter-current flow limitation (CCFL) in vertical pipes by using existing CCFL data. The characteristic length of w = D^(1-β)L^β (where D and L respectively denote the diameter and the Laplace capillary length) in the dimensionless velocity was different depending on the limiting location, and our results indicated that CCFL-L at the sharp-edged lower end, CCFL-U at the sharp-edged upper end, and CCFL-P inside vertical pipes are respectively expressed by β = 0(w = D), β = 1(w = L), and β ≈ 0.5(w ≈ D^0.5L^0.5). We also evaluated effects of fluid properties on CCFL in vertical pipes by using existing CCFL data. The most effective fluid properties is the liquid viscosity, and so we expressed the slope m and constant C_j in the Wallis type correlation with the viscosity ratio of gas and liquid (μ_G/μ_L). We classified three regions for effects of μ_G/μ_L on m and C_j and we obtained exponent functions of μ_G/μ_L for m and C_j in the case of the small μ_L (room-temperature to high-temperature water) for CCFL-L and CCFL-U except CCFL-P without high-temperature CCFL data. We evaluated CCFL characteristics in a pressurizer surge line with the sharp-edged upper end, and we derived a Wallis type correlation with β = 1(w = L), the slope of m = 0.94, and the constant of C_K = 1.24 ± 0.1. (author)