Loading...

Experimental Investigation of Water Desalination Using a Combination of Membrane Distillation and Natural Vacuum

Bahmanabadi, Amir | 2025

0 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58309 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shafii, Mohammad Behshad
  7. Abstract:
  8. The shortage of fresh water and lack of access to it have become one of the main challenges for various countries. Desalination of saline water has been recognized as the most effective solution to address this issue. Desalination of saline water is carried out using various methods, with membrane distillation (MD) receiving significant attention in recent years due to advantages such as utilizing surface evaporation, low sensitivity to feed water salinity, and the use of inexpensive materials. This study focuses on integrating membrane distillation and natural vacuum methods. The proposed method is evaluated in two sections: natural vacuum membrane distillation (NVMD) and air-gap membrane distillation under natural vacuum (NV-AGMD). According to the results, in the NVMD method, the water production rate for feed water with a salinity of 0.5 mol/L, a flow rate of 60 L/h, and temperatures of 45, 65, and 85°C is 5.5, 18.5, and 45.9 m³/day per square meter of membrane, respectively. Additionally, over time, due to an increase in condenser pressure, water production decreases. Therefore, if vacuum regeneration is performed every 6 hours, the water production rate increases by an average of 70% compared to the state without vacuum regeneration, while energy consumption does not increase due to the use of a water pump instead of a vacuum pump. Moreover, by reducing the air-gap pressure using natural vacuum in the NV-AGMD method, the flux can be enhanced. In this case, the water production rate for feed water with a salinity of 0.5 mol/L, a flow rate of 60 L/h, and feed water temperatures of 55, 65, 75, and 85°C is approximately 5.7, 9.5, 14.6, and 21 kg/h per square meter, respectively. On average, this represents about a 320% increase compared to the conventional AGMD method. Additionally, if the vacuum in the air gap is regenerated every 4 hours using natural vacuum, the water flux for 24 hours at temperatures of 55, 65, 75, and 85°C is approximately 8.7, 14.2, 21.2, and 29.7 kg/h per square meter of membrane, respectively. On average, this corresponds to about a 500% increase compared to the conventional AGMD method. Furthermore, the electrical energy consumption for producing 1 m³ of fresh water in the proposed method, without vacuum regeneration and with vacuum regeneration, is reduced by approximately 50% and 70%, respectively, compared to the conventional AGMD method
  9. Keywords:
  10. Desalination ; Membrane Distillation ; Noncondensable Gases ; Natural Vacuum ; Water Desalination

 Digital Object List

 Bookmark

No TOC