Process modeling and performance analysis of a productive water recovery system

In this paper, a single stage and double stage mechanical vapor recompression (MVR) system are designed and their performances are analyzed at different working conditions. The main purpose is to recycle water from the Reverse Osmosis rejected brine that is one of the main environmental challenges. A mathematical model for the MVR system is implemented and a sensitivity analysis is performed to investigate the effect of operational variables on the system power consumption and heat transfer area in both single stage and double stage MVR. An exergy analysis is performed to evaluate the improvement potential of the system performance based on the second law of thermodynamics. The results show that by increase of the saturation temperature difference of the single stage MVR from 10 °C to 15 °C, the total heat transfer area of the system decreases and the compressor power consumption increases by 50%. Almost 3.3% energy saving is achieved using the double-stage MVR instead of the single-stage MVR and the total heat transfer area is decreased by about 5.6 m2. The coefficients of performance of the single stage and double-stage MVR are 16.2 and 15.12, and the exergy efficiencies are 3.51% and 9.52%, respectively.