CFD-aided mathematical modeling of thermal vapor compressors in multiple effects distillation units

• A CFD-based correlation for mixing efficiency is proposed.
• Elevation of feed temperature leads to reduction of entrained flow rate.
• Increase of feed temperature decreases the nozzle throat and constant area diameters.
• The entrainment ratio sharply increases by rising of the suction temperature.
• Higher motive steam temperature leads to higher entrainment ratio.

In this study a mathematical investigation for the prediction of thermo-compressor performance in a multi-effect distillation unit (MED) is performed. The real gas equation is used to calculate the properties of the working fluid. It is assumed that mixing of the primary and entrained flows occurs at constant pressure inside the constant-area section of the thermo-compressor. The effects of variations in operating conditions such as motive steam pressure and temperature and suction and discharge temperatures on thermo-compressor performance are studied. Various numerical simulations based on the two-fluid multiphase flow formulation are performed. Based on the numerical simulations, a correlation for the calculation of mixing efficiency of motive and entrained flows inside thermo-compressors is proposed. Quantitative validation of data from the proposed mathematical algorithm with industrial data is also presented.