Onur Tokkan

Leidenfrost Self-propulsion of Cryogenic Droplets inside a pipe

Water droplets placed on a surface heated to a sufficient temperature (the Leidenfrost temperature) levitate on a film of their own vapour. A recent Nature article showed that adding a sawtooth pattern to the heated surface causes these levitating droplets to be propelled (even uphill!). Very recent work at Bath has shown that this propulsion can be achieved in mm diameter enclosed pipes. This opens the way to exploitation of Leidenfrost propulsion for active cooling systems that operate without moving parts and use waste heat energy for the thermal pumping effect. Onur will seek to extend this work by using AM techniques to create 3D printed cooling systems with internal ratchet structures. His work will focus on optimum fluid/surface choices (experiments have previously been confined to water) and ensuring AM quality is sufficient to reliably allow propulsion as surface roughness can cause an increase in the Leidenfrost temperature. The effect of pressure on heat transfer will be studied both experimentally and numerically and set in context against current systems.