Feasibility investigation of a humidification-dehumidification (HDH) desalination system with thermoelectric generator operated by a salinity-gradient solar pond

Abstract

Water distillation via solar energy is investigated potentially as an appreciable topic across the globe in recent decades. While many high-efficient solar collectors are developed for this objective, it is discovered that solar pond with big size can be more cost-effective than many types of high-efficient collectors. In pursuance of this objective, plausibility of extracting thermal heat from a salinity-gradient solar pond (SGSP) set-up for water distillation via a humidification-dehumidification (HDH) system is scrutinized under privilege of thermodynamics laws. Furthermore, due to the fact that solar pond's pumps consume more power for their task, two thermoelectric generators (TGEs) are posited to use waste heat of the discarded brine and distilled water to generate electricity for power demands. Single-criterion optimization is executed for the suggested set-up and the results are presented for the Urmia lake in Iran. Considering maximization of distilled water scenario, the findings outlined that 4.5 m3/h distilled water and 3.16 kW net electricity can be generated with cogeneration Gain-Output-Ratio (CGOR) of 1.56 and exergy-based CGOR (ECGOR) of 4.87%. Also, the designed desalination unit generated more fresh water between 22 May and 22 July for Urmia province, while more electricity is generated between 21 April and 21 May. Among all constituents of the introduced SGSP/HDH system, dehumidifier attributed as the major site of loss by exergy destruction of 15.23 kW. At last, an exhaustive parametric evaluation is established to scrutinize impact of some preeminent design parameters on the targets. It is exhibited that the CGOR can be maximized with desalination flow ratio, while the ECGOR can be maximized with lower-convective zone temperature.