Investigation of a distillation desalination system driven by solar and ocean thermal energy

Abstract

Ocean thermal energy is a stable and abundant marine renewable energy that can be adopted for sustainable desalination in remote islands. However, its relatively low available temperature difference restricts its application. Therefore, to manipulate ocean thermal energy while overcoming its unique small thermocline temperature gradient, a dual-energy-driven distillation desalination system driven by solar and ocean thermal energy is put forward. The merits of this system include resolving the nightly failure of solar desalination systems and higher productivity. To quantify the system potential, a numerical model is developed and thermodynamic analysis is conducted. A comparison between dual-energy-driven system and single-energy-driven systems is conducted. The results indicate that the yield can be significantly improved by simultaneously using solar and ocean thermal energy. A single ocean thermal energy-driven desalination can achieve the minimum freshwater productivity of 0.07 kg·h−1, while coupled solar thermal energy can improve freshwater yield to 1.21 kg·h−1, which is 30.1 % higher than that of a single solar desalination. The system power consumption is only 1.77 kW·h/ton. Furthermore, based on the actual meteorological data in Haikou, China, an annual freshwater productivity of 3524 kg (for a 1 m2 absorber plate area) can be obtained, corresponding to a gain output ratio of 0.44.