Capillary-driven low grade heat desalination

A capillary-driven seawater desalination method is presented in this study. The core part of the system is an open heat pipe which distinguishes from the regular heat pipe is that no freshwater flows back to the evaporator, but feeds with seawater instead. An experimental prototype is designed and established, which has proved that nearly 91.8 g/h of freshwater could be produced at 42 °C of heat source with an effective evaporation area of 50.24 cm2. The total dissolvable solids (TDS) of the produced freshwater is about 30 mg/L, far beyond the standard for drinking water. An industrial desalination unit has been established at Guangdong Yudeam power plant (Guangdong, China). The low temperature steam around 60 °C extracted from #2 steam turbine is considered as the heat source for the desalination unit anticipating a fresh water production rate of 45.7 kg/h. For wide operation temperature adaptability, particularly at lower temperatures, the presented desalination technique may have huge potentials for the applications of low-cost and low-grade waste heat. Advantages of this capillary-driven desalination are discussed and results from the experimental prototype and industrial unit are presented to demonstrate the feasibility of the novel method.