Hierarchical gradient mesh surfaces for superior boiling heat transfer

Abstract

• Hi-GM exhibits 313% and 811% enhancements in CHF and HTC over the plain surface. • Microchimney effect coupling with superior capillary enhances the performance. • Hi-GM transcends the classical predictions of capillary and bubble dynamics theory. • The concept of inducing bubble and liquid transport sheds light on thermal design. Engineered surfaces enabling remarkable phase change heat transfer have elicited increasing attention due to their ubiquitous applications in energy conservation and thermal management. Despite extensive efforts, designing micro/nanostructures that accelerate both the liquid wicking and bubble cycles to extend the boiling performance remains challenging. Here, we develop a hierarchical gradient mesh surface that exhibits exceptionally high critical heat flux (CHF) of 300 W/cm 2 and heat transfer coefficient (HTC) of 34.52 W/(cm 2 K), which are 313% and 811% larger than those of the plain surface with de-ionized water under 1 atmosphere pressure. By simply sintering multilayer meshes with controllable porosity and superhydrophilic micro/nanostructured coating, the surface developed is cost-effective, and capable of exhibiting strong wicking effect and rapid small bubble detachment characteristic via a chimney-like architecture. Such a rational design transcends the classical predictions of the capillary wicking model and bubble dynamics theory for superior boiling. The proposed concept of tailoring structures to induce bubble and liquid transport for efficient phase change heat transfer may point in a new direction for thermal engineering.