Experimental Investigation of Artificial Cavities Effect of Single-Phase Fluid Flow and Heat Transfer in Single Microchannel

Abstract

In this paper, an experimental study has been conducted to investigate the influence of artificial cavities (artificial nucleation sites, ANS) in a single microchannel on the characteristics of flow and heat transfer at a single-phase flow. The experiments were performed with deionized water as a working fluid at 30OC inlet temperature with a range (108.6-2372) of Reynolds numbers. Three models of the straight microchannel (model-1, model-2, and model-3) were manufactured of brass having a rectangular shape with a hydraulic diameter of (0.42 mm). Model-1 has a smooth surface, while model-2 has artificial cavities with a number of 40 ANS located on the base of the microchannel; along a line adjacent to one of the sidewalls. Also, the artificial cavities of model-3 exist at the base of the microchannel; along a line that is nearest to each sidewall for the microchannel. The number of ANS at each sidewall is 40 (i.e. the overall number of artificial nucleations is 80). The results manifested the enhancement of heat transfer by the presence of ANS for model-2 and model-3 as compared to model-1 by 15.53% and 16.67%, respectively. Also, the results proved that the fanning friction factor correlation for laminar and turbulent flow can predict very well the results (MAE=6.6-7.2%) and (MAE=4.1-7.7%), respectively. Also, the Nusselt number increases with increasing Reynolds number. However, the conventional correlation that predicted the experimental results is lower than the correlations (MAE=30.1%, 13.2% and 12.6%) for Model-1, -2 and -3, respectively.

Keywords

• microchannel
• single-phase flow
• friction factor
• nusselt number
• pressure drop