Energetic performance analysis of seawater desalination with a solar membrane distillation

In this paper, a study of the energy performance of a solar powered vacuum membrane distillation was investigated on four typical days that represent the four seasons of the year namely: the equinoxes (March 21st and September 21st) and the solstices (June 21st and December 21st), through the widely used energy criteria such as specific energy consumption, gained output ratio and heat recovery factor. The results indicate that the energy performance of the process is strongly linked to the solar irradiation and as long as the VMD is coupled with solar energy, the process could be competitive with industrialized desalination technologies such as RO, MSF and MED. Besides, the effect of the applied vacuum level on the specific energy consumption was examined. Obviously, the results reveal that for minimum SEEC an optimal vacuum pressure is between 5000 and 10000 Pa. As well a technique to optimize the energy performance by recycling hot cooling water, used for steam condensation, was discussed. An amelioration of about 35%, 26% and 31%, during the hottest day (June 21st) and of about 22%, 19% and 21%, during the coldest (December 21st) in the GOR, the SEC and the daily production could be achieved.