3-D modeling of the ABB lummus heat transfer 'HELIXCHANGER~(TM)' using CFD

摘要

Detailed three-dimensional CFD simulations have been performed for the ABB Lummus Heat Transfer helical heat exchanger "helixchanger~(TM)", The CFD simulations have been performed with the HEATX simulation package. The simultion accounts for the complex helical geometry of the baffles, leakages, and nozzle entrance and exit. Three cases are presented corresponding to helix angles of 10 deg, 25 deg, and 40 deg. Inspection of the computed flows reveals distinct inner and outer regions, with the outer region showing a plug flow characteristic. However, the inner region displays recirculation zones due to back mixing at the small helix angle but this strong mixing gives desirable temperature uniformity. Comparison with plug flow showed the helixchanger had a fluid turn ratio of 0.64, 0.78 and 0.77 for the 10 deg, 25 deg, and 40 deg helix angles, indicating more overall plug-like flow for the higher helix angles. Computed pressure drops compare reasonably wellwith ABB Lummus Heat Transfer correlation results, although nozzle entrance and exit losses require further study.