Thermodynamic Analysis of Vortex-Humidification-Dehumidification Desalination (V-HDH)

Abstract

In recent years, water stress has become a global crisis due to climate and demographic changes and lifestyle changes. Freshwater production from the sea using various processes is known as the most important solution to deal with this crisis. Among these processes, the humidification-dehumidification process has been considered by the scientific community as a flexible and low-cost method. The present work has investigated the performance of vortex-humidification-dehumidification water desalination cycle. The existing system is a dehumidifier-dehumidifier type, in which a vortex tube has been added. According to the structure of the vortex tube, its hot air outlet has been used to increase the possibility of moisture absorption in the humidifier and its cold air outlet has been used to increase the amount of condensed water in the humidifier. According to the second law of thermodynamics, the performance of the cycle has been studied. In the analysis of multi-flow cycles with heat and mass transfer, the commercial software EES has been used to solve the equations. The fresh water output for specific conditions (sea level, air temperature 35 degrees Celsius and relative humidity 30 percent) is equal to 7.85 kg/h and the research results show that the Gained-Output-Ratio is equal to 1.189. It is shown that the use of the vortex tube and the consequent increase in air temperature at the inlet of the humidifier and the use of the second dehumidifier in the cycle increase the production of fresh water.

Keywords

• energy efficiency
• vortex tube
• desalination
• humidification dehumidification