Study of a novel Humidification-Dehumidification Desalination system hybridised with Indirect Evaporative Cooling and Vapour Compression Refrigeration

In this work, a novel configuration of a Humidification-Dehumidification (HDH) Desalination system, called Enhanced Indirect Cooling Evaporative Desalination-Closed cycle (EICED-C), obtained by the hybridisation of an HDH configuration with Indirect Evaporative Cooling (IEC) and Vapour Compression Refrigeration (VCR) devices, is presented. The IEC is intended as an efficient saltwater evaporator-air humidifier. Both coils of VCR are employed: the hot coil to heat airflow enhancing the saltwater evaporation process and the cold coil to provide the cooling capacity for pure water recovery. The system is closed on the air side and two versions of closing solutions are shown and compared. The cycle is theoretically introduced and modelled, using data from commercial devices to give an applicative target to the study, and subjected to parametric analysis. In the best operative conditions, version 1 shows a SEC (energy efficiency) of 172.3 kWh/m3 and a RWA (water recovery) of 5.2∙10-6, version 2 a SEC of 159.9 kWh/m3 and a RWA of 5.6∙10-6. Air-side pressure drops and the related consumptions for air moving are counted and their weight in the optimisation of efficient HDH systems is highlighted. The obtained results lead to consider these proposals as very competitive in the field of HDH desalination.