Study of Condensation on PDMS Substrates for Enhanced Solar Still

Abstract

Abstract: Condensation surfaces are found in many applications from solar stills to phase change heat exchangers, solar condensers etc. In all these applications, it is important to increase the condensation efficiency by engineering the surface which yields better condensation properties that are suitable for targeted needs. In the current project, we envisage such an effort where metal elastomeric composite substrates are employed to increase condensation efficiency.

We use Polydimethylsiloxane (PDMS) as a choice of elastomer and Aluminum particulates as the choice of the metallic inclusions. Write after preparing the substrates of different portions of metallic particulate inclusions and condensations, tests are carried out on each substrate separately. Here we prepare a few substrates by varying the Aluminium metallic particle mass fraction over five decades from 10^-6 to 10^-8. The substrates thus obtained are used in condensation tests. From the measurements, a dew condensation rate was calculated. The tests were repeated four to five times to ensure repeatability of the measurements. Care was also taken to ensure that all the measurements were obtained in the same atmosphere.

The dew condensation rate was studied by varying the Aluminium mass fraction in the substrate. A non-monotonic behavior was observed wherein high condensation rates were obtained for an Aluminium mass fraction of approximately 5*10^-4 g. For all other mass fractions, the condensation rates are less than this above condition. Therefore, it can be concluded that this is an optional mass fraction for which dew condensation efficiency was the highest