A large proportion of the world's population still has no access to clean water. New, innovative and more cost-effective methods of producing drinking water need to be developed. Seawater desalination is one of the most frequently investigated technologies in this area. Heat exchangers offer the greatest potential for a noticeable reduction in the cost of drinking water treatment. High energy flows are required to heat up or cool down working fluids. Droplet condensation is an interesting field for research in the area of heat transfer. Experiments have shown that the heat transfer coefficient in droplet condensation is many times higher than in film condensation and that the efficiency of heat exchangers can therefore be significantly increased.

In the project, hierarchically structured surfaces are to ensure controlled droplet condensation and this is to be used for a more efficient heat transfer process. The LRF is working in cooperation with Prof. Oesterschulze's PTNano working group and is researching how to influence condensation behavior with regard to the targeted modification of surfaces. By increasing the hydrophobicity of the surface, the wetting properties are reduced and thus the conditions for stable droplet condensation are to be created.

• Production and characterization of micro- and nanostructured surfaces
• Establishment of a hot embossing process to create microstructures on various polymers
• Testing the influence of the newly created surfaces on heat transfer and condensation behavior
• a standardized test apparatus for:
  • Observation of the condensation behavior
  • Determination of the heat transfer coefficients
  • Analysis of the droplet size distributions

Raphael Raab