Experimental Study of the Performance of a Novel Swirl Flow Separator for High Salinity Desalination Applications

There are limitations on high salinity applications for most of the current commercial desalination platforms such as the commonly adopted Reverse Osmosis (RO) technique. Other prevalent thermal desalination methods such as Multi Stage Flash Evaporation (MSFE) or Multi Effect Distillation (MED) are capital intensive and less efficient for high salinity applications such as brackish water, or brine waste from desalination or process industries, which typically exceeds 3.5% salinity and is disposed off in the water bodies as waste, which in turn, has detrimental environmental effects. This study is focused on experimental investigation of a novel swirl flow separator which leverages dynamic flash evaporation for higher salinity applications. The proposed concept results in a smaller form factor by using 2 separator stages which could potentially drive down the cost of desalination. The novel apparatus has been tested extensively in previous studies for desalination of feed water with 2% salinity. The aim of this study is to experimentally evaluate the performance of this novel 2-stage swirl flow apparatus for feed water with higher salinity levels, with concentration of 10% salt by mass. The ultimate goal is to demonstrate the feasibility of this experimental apparatus for desalination applications involving feed water with higher salinity values and to demonstrate the insensitivity of the apparatus to varying salinity levels in the feedstock. The thermal-hydraulic performance and efficacy of this lab-scale prototype for feed water with 10% salinity is compared with that of experiments involving feed water with 2% salinity level (from previous reports in the literature). These comparisons are performed by determining the thermal-efficiency, phase separation efficiency and collection efficiency values for supply temperature of 80°C (and for five different values of flowrates of the feedwater). The pure water collected downstream in the condenser is observed to have a salinity lower than 0.01% salt concentration by mass regardless of the feed water salinity levels, thus demonstrating the insensitivity of the novel apparatus for desalination.