Publication

Abstract : This study evaluated the thermodynamic performance and energy recovery potential of a lab-scale supercritical water desalination system with a double-tube heat exchanger under varying feed flow rates and NaCl concentrations (1–10 wt%), aiming to reduce the high thermal energy demand required to achieve supercritical conditions. Experiments at > 374 °C and > 22.1  MPa showed that higher flow rates and salinity enhance convective heat transfer and energy recovery due to reduced specific heat capacity of hypersaline feeds. Thermal energy recovery with hypersaline brine led to a significant 48.9 % reduction in net heat input to feed for supercritical operation and achieved near-complete salt precipitation, indicating non-requirement of pre- or post-treatment. Notably, better preheating at higher feed salinity level aided in better phase separation efficiency contributing to better distillate quality. The system recovered up to ∼ 0.23 kWhth/kgfeed, demonstrating the role of hypersaline feed in reducing the energy demand to achieve supercritical temperatures. These findings offer critical insights for scaling up of the first-generation supercritical water desalination zero liquid discharge process as a viable solution for treating hypersaline brines sustainably without generating concentrated waste.