Methodology for more accurate assessment of heat loss in microchannel flow boiling

Abstract

Flow boiling in micro-channels is a technology that can potentially be employed for cooling of next generation electronics. High heat transfer coefficient, better temperature uniformity and small pumping power requirement compared to single phase flow are the main advantages of this technology. Advancement in this field is checked by divergence in trends across various groups which warrents more reliable methods to acquire and post-process experimental data. Heat loss estimation methodology and evaluation of the heat transfer coefficient and exit vapour quality can be further refined to realize reliable data-sets. This article proposes the need to adopt two different methods to account for heat loss, one for the calculation of the heat transfer coefficient, wall temperature and wall heat flux while the other for calculation of exit vapour quality during flow boiling. Experimental results bolstering the proposed need are also presented. Two test-sections each having a single finless microchannel of length 25400 μm and width and height of 2540 μm × 420 μm as well as 2540 μm × 150 μm were used. The difference between the heat loss estimated by the two methods is quite substantial hence justifying the endeavour for better heat loss estimation methodology.