Nucleate Boiling Heat Transfer Investigation Using Micro and Nanostructured Plates

Abstract

-In this study, heat transfer performance of micro and nanostructured plates embedded into a rectangular microchannel was experimentally investigated for their potential use in cooling applications. A simple and environmentally friendly technique was proposed to provide the micro and nanostructured plates having superhydrophilic property. Aluminium alloy (Al Alloy) 4041 substrates of 1.5 × 1.5 cm were roughened by sandblasting method using medium size aluminum oxide abrasive to provide microfeatures; followed by hot water treatment (HWT) process in which nanograss structures were developed on the microstructured substrates. The micro and nanostructured plates were placed near the exit of an aluminum (Al) microchannel with a length, width, and depth of 14 cm, 1.5 cm, and 500 μm, respectively. Four cartridge heaters connected to a DC power supply were utilized to apply heat to the test section. De-ionized (DI) water was used as the working fluid and passed through the microchannel using a micro gear pump at three mass fluxes of 100, 300, and 500 kg/m 2 s. The test section dimensions and experimental parameters were selected such that fully developed flow conditions were obtained. The results from the microchannel with untreated Al alloy surfaces were considered as the baseline data. Experimental results of the micro and nanostructured plates revealed that there is no significant change in nucleate boiling heat transfer compared to the control sample. The reason is related to wettability and roughness of the micro and nanostructured plates.