Analysis of a hybrid Thermal Vapor Compression and Reverse Osmosis desalination system at variable design conditions

This study proposes different configurations of TVC (Thermal Vapor Compression-Reverse Osmosis (TVC-RO) hybrid systems. The energy-based analysis is used as a quantitative measure to evaluate the system performance by Specific Energy Consumption (SEC) and Production Ratio (PR). The effects of the design parameters including boiling temperature, seawater temperature, compression ratio, motive steam pressure, leakage ratio and mixing rate of the pressure exchanger are obtained through a parametric study. Our results indicate that a better system performance can be achieved by the proposed serial TVC-RO system than the parallel and stand-alone system. A low sea temperature contributes to a better hybrid system performance, and a high boiling temperature results in a high PR. An optimum boiling temperature exists for the lowest SEC when seawater is above 11 degrees C. For the steam ejector, a low compression ratio helps to improve system performance, and SEC increases consistently while the PR increases first and then decreases with the increasing motive steam pressure. For the pressure exchanger in the RO process, a low mixing rate helps in improving the overall system performance, and a low leakage ratio is also advantageous as it has a more sensible improvement on SEC than on the PR.