Improved heat dissipation performance of nano-porous wicking evaporator by structural modification: A numerical study

Abstract

Capillary-driven evaporation of liquids play an important role in the thermal management of electronic devices. The recently developed nano-porous evaporator supported by microchannels proved to be promising in heat dissipation and energy saving. In this work, we proposed novel modifications to the nano-porous evaporator structure which could simultaneously enhance the dry-out heat flux and heat transfer coefficient. These include a non-uniformly distributed nanopore size and a membrane with shortened length. By conserving the farthest nanopore size and enlarging the closer nanopores, or simply removing part of the membrane, the pressure drop and thermal resistance of the evaporator were both minimized. Numerical approach was developed for simulating the heat transfer and fluid flow in the nano-porous evaporator. Kinetic boundary conditions were applied at the liquid–vapor interface to simulate evaporation. Results of temperature and pressure fields were obtained. It was found that the evaporative thermal resistance and the pressure drop in microchannel played dominant roles in determining the evaporator performance. The structure with partial membrane 10 μm in length had the best heat dissipation performance, which improved the dry-out heat flux and heat transfer coefficient by 22.3% and 139.5%, respectively, compared to the benchmark evaporator structure.