Hu Xuejiao

Capillary-driven seawater desalination

We demonstrate a novel capillary-driven seawater desalination system. The essence of the system is an open loop heat pipe. Seawater is evaporated at the outer surface of the wick structure of the “heat pipe”, where a capillary pressure is developed as the driving force to ensure the continuous operation of the system. The produced vapor is then condensed into fresh water in a condenser. The difference from a regular heat pipe is that the evaporator is not fed back with the condensed water, but with seawater instead. With a heat source at 40℃, the fresh water production rate is achieved up to 91.8 g/h for an effective evaporation area of 50.24 cm2. The TDS (total dissolvable solids) of the produced water is less than 30 mg/L, far beyond the standard for drinking water. For wide operation temperature adaptability, particularly, at low temperatures, the presented desalination technique may have big potentials for the use of low-cost and low-grade heat energy to produce fresh water.