Black Fabric as low cost efficient humidifier/solar collector in a humidification-dehumidification solar desalination

  • Pairoj Kiatpanya

Student thesis: Master's Thesis

Abstract

Water scarcity affects people all around the world and the situation is getting worse, especially in the developing countries. Desalination is one possible solution since 97% of water on the earth is salty. The biggest hindrance in the developing countries to distill sea water is the lack of energy sources and the high component’s cost. The requirement to overcome this crisis is to develop a low cost desalination system that can be integrated with the energy sources that are available in the region. One potential technology is the solar-driven humidificationdehumidification (HDH) desalination. This thesis investigates a new idea of HDH solar desalination process using a perforated black fabric as a humidifier and a solar collector. Two barriers for the solar HDH process are the low water yield and the high equipment cost. The proposed idea is to attack that barriers. The black fabric provides several advantages over a conventional solar collector and a humidifier such as low cost, unbreakable, easy to manufacture and light weight. Also, it combines a humidifier and a solar collector into a single component. The black fabric is perforated to capture humid air and painted black to absorb solar energy. Sea water is flowed down along the fabric by gravitational force, absorbing solar energy. An air is drawn from the surrounding to a plenum behind by a fan that is driven by a small solar panel, creating a boundary layer at the surface. The air takes heat and moisture as it flows through the perforations. The optimal air and water flow at any instant is factors of boundary conditions; sea water temperature, ambient temperature, ambient humidity, incident solar flux and wind speed. The mathematical model of the black fabric as humidifier/solar collector in the HDH solar desalination was developed. The black fabric model was combined with a counter-flow dehumidifier and a liquid-to-liquid heat exchanger to create a complete HDH solar desalination system. The model was driven by the Typical Meteorological Year (TMY) data, including DNI, DHI, temperature and humidity, and monthly sea water temperature data from the C-GLORS to predict the annual water yield by optimizing the system at every hours. The model predicted a yearly water productivity at 2,000 liter of water per square meter of solar collector. An average gain-output ratio (GOR) over the year was 0.714553 with the specific power consumption of 6kWhe=kL. The results were compared with a conventional solar still, a conventional HDH solar desalination system and a reverse HDH solar desalination system. Finally, the model was verified with experimental data.
Date of AwardMay 2015
Original languageAmerican English
SupervisorPeter Armstrong (Supervisor)

Keywords

  • Humidification
  • solar desalination
  • dehumidification
  • black fabric
  • solar energy
  • solar desalination system.

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