Numerical Investigation of erosion–corrosion behavior and flow-distributor performance in an air cooler under CO 2 -containing condensate conditions

Localized tube leakage in the E301 molecular-sieve regeneration-gas air cooler was investigated using a three-dimensional computational fluid dynamics–discrete phase model (CFD–DPM). Gas–liquid hydrodynamics and droplet-induced erosion were analyzed, while CO2 corrosion was calculated using the NORSOK M-506 model. Confinement within the inlet header redirected both inlet streams, generating preferential jets, tube-to-tube flow maldistribution, and radial secondary flow near the first two tube rows. The primary droplet-impingement hotspot was located on windward wall A of tube No. 13 in the second row, consistent with the field-observed leakage location. At this hotspot, the erosion-to-corrosion rate ratio (ER/CR) was 3.57, indicating an erosion–corrosion-dominated regime. To mitigate this localized damage, a cylindrical-element flow distributor was designed to redistribute inlet momentum and disperse droplet trajectories. It reduced the maximum erosion rate at the hotspot by 59.0%, while the maximum CO2 corrosion rates on walls A–D decreased only slightly. The hotspot ER/CR consequently decreased to 1.51. These findings identify inlet-driven droplet impingement as the dominant contributor to localized tube-wall loss and demonstrate that inlet-flow redistribution effectively mitigates the associated damage.