Airflow‐enhanced evaporation–condensation seawater desalination using residential air conditioner waste heat

Abstract

Water scarcity remains a major global challenge, particularly in developing countries with limited freshwater access. At the same time, the increasing use of residential air‐conditioning (AC) systems generates substantial low‐grade waste heat that is typically rejected into the environment. This study investigates a household‐scale evaporation–condensation desalination system driven by waste heat recovered from a residential split‐type AC unit. The proposed system integrates vortex‐generator‐assisted airflow enhancement within a compact evaporation channel to intensify heat using channels with different cross‐sectional areas under vortex‐generator (VG) and non‐vortex‐generator (NVG) configurations. Air temperature, relative humidity, evaporation rate, seawater salinity, and AC coefficient of performance (COP) were measured, while computational fluid dynamics (CFD) simulations were performed to analyze airflow and evaporation behavior. The results showed that vortex generators enhanced airflow mixing and evaporation performance. Maximum freshwater production of approximately 950–980 mL/h was achieved at channel cross‐sectional areas of 0.015–0.025 m ² . Although COP decreased from 3.92 to approximately 3.02 under the most restrictive channel configuration, the values remained within the typical residential AC operating range. The CFD predictions showed strong agreement with experiments, with R ²  > 0.95 and average deviations below 10%. A preliminary economic analysis estimated the operational cost at approximately USD 0.017/L of freshwater produced. The proposed system demonstrates promising potential for decentralized and energy‐efficient household freshwater production using readily available AC waste heat.