ENHANCED THERMAL INSULATION PROPERTIES OF CONFINED SUPERHYDROPHOBIC SURFACES
The insulating capacity of superhydrophobic (SH) surfaces in confined liquid systems (range) is investigated for potential thermal micro-devices and MEMS application. The study involves analyzing the transient cooling of hot liquid films confined in rectangular slits with walls made of polyimide materials and having typical patterns of pillars and grooves causing superhydrophobicity. A periodic SH patch consisting of pillars and grooves with air occupying the latter is considered. A 1-D transient conduction modeling approach is adopted applying appropriate flux boundaries that incorporate the combined resistances of air film present in grooves and the wall solid. An exact 2-D analysis is conducted using CFD simulations. Cooling is characterized as function of external Biot number. Both CFD and modelling results reveal a delay in cooling for SH with respect to smooth (SM) surface. The analysis highlights the scope of using SH walls for insulation of hot fluids industrially.