Evaluating the seawater desalination potential of an air-seawater system: through thermodynamic analysis and simulation of an indirect evaporative cooling desalination system

Abstract

This paper explores the desalination potential of a non-equilibrium air-seawater system. It provides calculations for thermodynamics at three different precision levels and introduces new insights, including the concept of system exergy and reversible transitions, to enhance the understanding of the evaporative cooling and desalination processes. The results indicate that for an air-seawater system at 30 °C, which includes 1 kg of dry air at a relative humidity of 45 % and 1 kg of seawater at a concentration of 3.5 %, there is a desalination potential of 0.138 kg of water product. Furthermore, a novel desalination process that utilizes an indirect evaporative cooling (IEC) chiller is designed, modeled, and simulated to estimate its freshwater production capacity. The simulation reveals a daily water product of 0.503 m3 for specific 1 m3*s−1 of air flow rate. A comprehensive sensitivity analysis of parameters is conducted based on this model. In comparison to the thermodynamic calculations, the simulated model exhibits a reversible efficiency of 3.6 % under typical conditions, suggesting there is ample room to further exploit the desalination potential of the non-equilibrium air-seawater system. Additionally, by incorporating comments on irreversible loss analysis, several optimized strategies are proposed. Considering the exergy inherent in non-equilibrium air-seawater systems is abundant, the concept of desalination based on non-equilibrium air-seawater system holds promise to yield economic benefits and reduce carbon emissions.