CFD and experimental investigation of the gas-liquid flow in the distributor of a compact heat exchanger

High performance of compact heat exchangers is conditioned by correct fluid distribution. This is especially true for gas-liquid heat exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels. The present study deals with the simulation and experimental investigation of the two-phase distribution and flow regimes in a distributor located at the bottom of the cold flow pilot plant of a vertical compact heat exchanger. Air and water are the working fluids, and the range of superficial velocities inside the distributor is 0.9-8.8 m s^-1 and 0.35-0.8 ms^-1, for air and water respectively. Three-dimensional Volume Of Fluid (VOF) simulations are performed and compared to experimental distributions, pressure drops, and visualizations. (authors)