| Abstract |
It has recently been reported (2013) that, when a low-concentration suspension of metal or carbon nanoparticles dispersed in water is illuminated by sun light, water vapor well above 100◦C can be produced with an estimated overall energy efficiency of 24%, and only marginal heating of the bulk water [1–3]. This newly discovered direct conversion of sun light into steam is sensational and has tremendous potential for applications e.g. in solar energy conversion. The underlying physics of this phenomenon is however not understood at all: one would expect the emerging vapor bubble to collapse and condense immediately once it gets into contact with the cold liquid. In this project we want to reveal the underlying physics of the process, combining molecular dynamics simulations as we previously performed for surface nanobubbles [4, 5] with level set methods for vapor bubbles [6]. Our working hypothesis is that vapor bubble stability can only be provided thanks to gas dissolved in the liquid, similarly to what we have theoretically and experimentally shown in ref. [7] for ultrasonically driven vapor bubbles. Our ultimate aim is to achieve a satisfactory physical understanding of the process in such a way that it can eventually be optimized. |
