Numerical investigation on steam flow and resistance to thermodynamic losses inside the full-scale low-temperature multi-effect desalination evaporator.

3D numerical simulation on the steam velocity field and flow resistance configuration in the fullscale low-temperature multi-effect desalination (LT-MED) evaporator were conducted and analyzed. The complicated two-phase water-vapor flow through the tube bundle was modeled using the single- phase vapor flow through the porous media (PM) model, which could simplify the effect of anfractuous geometry of the flow path and interactions between the two phases in the tube bundle. A PM model has been validated by additional experimental results. 3D numerical results were justified between the literature and real LT-MED plants. The numerical results suggest that the steam velocity in the tube bundle ranges from 1 to 12 m/s and presents different variation trends along the direction of the tube row, tube column, and tube length. In the axial channel, steam velocity first exhibits a rising tendency up to maximum of 50 m/s close to the outlet and then greatly decreases beyond the outlet. The components of steam flow resistance comprise tube bundle, demister, steam channel, and tube-side condensation resistances. The largest flow resistance is contributed by the axial steam channel, accounting for 57.6% proportion. The small steam flow resistance with a total of 381.6 Pa in the first-effect evaporator causes a significant reduction in the effective heat transfer temperature difference by a proportion of 12.2%. This study endeavors to find a new possibility of numerical simulation for the entire LT-MED evaporator, which could provide a good reference to engineering-optimized design and modeling of the LT-MED running condition. [ABSTRACT FROM AUTHOR]