Experimental insights into the performance of a compact desalination system

A pilot-scale desalination system capable of producing 15 litres of distilled water per hour has been designed, fabricated, installed and experimentally tested using both tank water (800 ppm) and sea water (36,000 ppm). The major components of the system are a flash chamber, a gasketed plate heat exchanger (GPHX) and an ejector. The flashed steam at an average temperature of 75°C is produced in a flash chamber by feeding hot water from a constant-temperature water bath. Then, steam from the flash chamber condenses on the GPHX hot side, releasing latent heat to cold water circulating on the cold side, which absorbs the heat to form distillate. The condensed distillate water is stored in the distillate tank and pumped back to the water bath. Similarly, the brine water from the flash chamber is also pumped back to the water bath. During experimentation, the maximum temperature difference between the inlet and outlet on the hot side of the GPHX was realised to be 46°C, and the average quality of the distillate water was in the range of 10–15 ppm. It is also observed that employing GPHX results in a 30% – 40% efficiency increase compared to shell and tube heat exchangers. In addition to experimental analysis, thermodynamic and economic analyses are conducted to understand the system’s behaviour and its potential for large-scale production. An economic feasibility analysis shows that using GPHX can lower the total system investment cost by 10% – 30%, reducing the cost per cubic metre of fresh water for large-scale production. This study addresses a critical gap in desalination technology by developing a compact system using GPHX, which reduces system size and cost while maintaining high efficiency, unlike conventional shell and tube based designs.