Abstract

The paper investigates the design and performance of humidifiers used in low-grade heat-driven desalination systems. It reviews the advantages and limitations of common humidifier types and presents an experimental study of a film-type humidifier configured as a vertical acrylic tube. Experiments examined hydrodynamics and heat and mass transfer over air mass flow rates of 7.4–35 kg/h, water mass flow rates of 10–80 kg/h, inlet water temperatures of 28–59 °C, air pressure drops of 19–324 Pa, water pressure losses of 22.3 kPa, and heater power inputs of 90–554 W. Optimal operating conditions were identified to maximize system performance and energy efficiency. A thermodynamic model based on heat and mass transfer equations was developed and validated. Compared with other humidifier designs, the film-type humidifier achieved the highest evaporation rate at equivalent operating conditions while maintaining minimal aerodynamic and hydraulic resistance, thereby reducing electricity consumption for air and water circulation without performance losses.