Nucleate boiling heat transfer enhancement using nanostructured al-alloy plates

Official URL: http://dx.doi.org/10.1115/MNHMT2016-6582

Bubble departure frequency and active nucleation site density are two main factors that affect the nucleate boiling heat transfer. The potential enhancement of boiling heat transfer can be accomplished by surface modification. This treatment can be realized with changing parameters such as porosity, tilting angle and cavity radius. In this study, effects of different nanostructured Aluminum-Alloy (Al-Alloy) 2024 sheets on subcooled boiling heat transfer are investigated. A simple and environmentally friendly technique is used in order to produce these plates that are immersed into boiling deionized water for 20, 60 and 120 minutes. To examine boiling heat transfer characteristics, nanostructured plates are placed inside a rectangular channel. The channel is heated through four cartridge heaters connected to a DC power supply while deionized water is pumped inside using a micro gear pump at constant mass fluxes of 50 kg/m2s, 75 kg/m2s and 125 kg/m2s. It was found that an increase in nano-structure height leads to higher boiling heat transfer coefficients. Furthermore, a high speed camera system was used to investigate flow patterns in the microchannel. Visualization results indicated that bubbles movde faster the nano-structure height increased.