Continuous vapor generation for thermal-desalination applications using a thermosyphon based heat localization strategy

Solar-based interfacial vapor generation techniques have received fresh attention lately, for generating potable drinking water for remote regions application. However, fouling due to salt accumulation and low water productivity has limited their commercialization. Decoupling of the solar irradiation absorbing surface and the vapor generating surface, is a technique recently preferred to address the above shortcomings. A thermosyphon-based decoupling strategy, enabling provision for latent heat recovery, and which is not prone to salt-fouling, is proposed here for the first time. In this strategy, the evaporator section is used for absorbing the solar irradiation energy whereas, the condenser section attached with a wick is the vapor generating surface. The optimal filling ratio (40 %) of the working fluid, for the operation of thermosyphon with the least thermal resistance, to achieve maximum solar-to-vapor conversion efficiency (81 % for 1-Sun) is identified. The proposed strategy is then made to undergo a 7-Day trial with 8-h of operation (with external input heat flux) followed by a 16-h of nighttime (without any external heat flux). Thus, the proposed strategy can successfully generate vapor continuously with a reasonable solar-to-vapor conversion efficiency of ~73 %, better than the recently reported studies that have shown long-term reliability. [Display omitted] •Novel thermosyphon-based solar heat-localization strategy for desalination•Provision for latent heat recovery in a ‘front-side evaporation system’•Easily scalable, fabric based wicking material requiring no advanced wick coating material•Suitable for incorporation of commercially developed technologies, like flat-plate solar collectors•Continuous, reliable vapor generation for 1-Sun without accumulation of salt deposits in the wick