SUPERWETTING SURFACES FOR DIMINISHING LEIDENFROST EFFECT, METHODS OF MAKING AND DEVICES INCORPORATING THE SAME

Technology

Surface roughness can be used to create a superwetting surface that can fundamentally alter droplet-surface interactions to continuously rewet the surface and prevent vapor film formation. Micro scale square posts are fabricated on silicon wafers with photolithography followed by a reactive ion etch. Silica particles with different diameters, 15-75nm, are spin-coated and sintered on the substrates already having micro scale square posts to create a hierarchical structure. The textured surfaces significantly enhance nucleate boiling and diminish the Leidenfrost limits, which increases heat transfer and reduces dryout. 

Problem Addressed      

Heat exchangers use boiling to transfer heat away from a solid. However, boiling is limited by the critical heat flux (CHF), which occurs at the Leidenfrost point, where a vapor is generated between the droplet and solid surface. The vapor causes heat transfer via conduction, which leads to dry-out and slows down heat transfer. A superwetting surface reduces the effects of the Leidenfrost effect by preventing vapor formation and continuously rewetting the surface; therefore, improving overall heat transfer.  

Advantages

• Increases critical heat flux
• Increases boiling efficiency