Research on Two-phase Flow Distribution in a Vertical Multi-branch Header

－Numerical Simulation of Maldistribution and Liquid Reverse Flow condition－

Abstract

Authors applied one dimensional computational model of Watanabe and Katsuta 5 branch headers to the shunt characteristics of vertical header type distributor with more than 30 branches which we clarified in the experiment and verified the accuracy and calculation time and further LBL (Liquid Branch Limit) model was newly studied using the flood reduction formula in order to predict the splitting characteristics at the time when the liquid refrigerant failed to reach the upper part of the header important for equipment design. As a result, even in the header exceeding 30 branches, the Watanabe model predicts the liquid refrigerant flow distribution characteristics in the range of deviation 0 to -0.6, and the calculation time is less than 10 minutes and it was confirmed to be industrially effective. By applying the LBL model, it is possible to predict the liquid refrigerant arrival height ratio to be ± 20 points and the liquid refrigerant flow deviation within ± 0.2, and the refrigeration flow distribution prediction accuracy under the liquid refrigerant unreachable condition is improved compared with the conventional method.