Design and construction of a desalination prototype based on HD (Humidification-Dehumidification) process

The paper deals with a low-temperature thermally driven desalination unit exploiting the HD (humidification/dehumidification) process. The system is a closed air cycle unit and is based on a single-effect humidification/dehumidification technique: heated seawater is introduced into the humidification section of a closed tunnel to saturate the circulating air; then the water vapor in moist air separates within the condensation column, where freshwater production takes place. A HD desalination prototype has been designed, assembled and fully instrumented in order to monitor all physical quantities and to evaluate the performance under different operating conditions. The prototype has been experimentally investigated on a test facility established at the Bergamo University Labs. The results of the measurement campaign are presented and discussed. A computer code for simulating the desalination process has also been developed and it was validated by the experimental data. The modeling procedure investigates air and water thermodynamic properties across every component and allows to predict the HD desalination unit performance, varying seawater and air flow rates, the heat source temperature level and the heat exchanger surfaces.