Design, fabrication and nucleate pool-boiling heat transfer performance of hybrid micro-nano scale 2-D modulated porous surfaces

Future technological products are increasingly becoming compact, integrated and multi-functional with higher heat loads in confined spaces. This has impelled the quest for improved heat management solutions to ensure the devices maintain their full performance as designed. Due to the associated latent heat, nucleate pool-boiling heat transfer (NBHT) systems are proven to dissipate the high heat flux at low-temperature gradients. NBHT systems with nano-scale and micro-scale porous structured surfaces are reported to possess enhanced heat transfer coefficient (HTC) and critical heat flux (CHF). The potential synergistic benefits of combining these two unique structures into an integrated surface coating fabrication technology have been a key question of interest. This study aimed to investigate the effect of uniformly coated nanoparticles on 2-D modulated micro-porous surfaces in NBHT. The NBHT performance of four different surface types; (1) flat untreated copper surface (UnCu surface), (2) nanocoated copper surface (NPC surface), (3) 2-D modulated micro-porous surface (MMPC surface), and (4) hybrid micro/nano-scale 2-D modulated porous coated surface (HMPC surface) are investigated. The UnCu surface and MMPC surface are employed for uniform nanoparticle coating to fabricate NPC surface and HMPC surface, respectively. Morphological characteristics of the surfaces were observed using the scanning electron microscopy (SEM). According to the results, the NPC surface and MMPC surface showed an enhanced NBHT performance by 81.6% and 50.6% improvement in CHF and 130.3% and 45% enhancement in HTC, respectively. However, as compared to the MMPC surface, the NBHT performance of the HMPC surface decreased. The average reduction in CHF and HTC of the HMPC surface was 16.8% and 24%, respectively. The reduction in the NBHT performance of HMPC is explained by the deterioration of the capillary wicking characteristics of the MMPC surface.