This paper verified the macro-to-micro-scale transitional criterion BoRel0.5 = 200 proposed by Li and Wu [W. Li, Z. Wu, A general criterion for evaporative heat transfer in micro/minichannels, International Journal of Heat and Mass Transfer 53 (2010) 1967–1976] because data points where BoRel0.5 ≤ 200 and BoRel0.5 > 200 show very different trends for the entire database (1,672 data points). For the 859 data points with BoRel0.5 ≤ 200, the boiling number at CHF decreases greatly with length-to-diameter ratio Lh/dhe when Lh/dhe is small, while Lh/dhe presents negligible effect on the boiling number when Lh/dhe > 150. For the region where Lh/dhe ≤ 150 and BoRel0.5 ≤ 200, a simple saturated CHF correlation was proposed by using the boiling number, length-to-diameter ratio, and exit quality. Heated length and heated equivalent diameter were adopted in the length-to-diameter ratio, considering the actual heat transfer conditions. A combined dimensionless number WemCal0.8 was introduced to correlate the micro/mini-channel database for the region: Lh/dhe > 150 and BoRel0.5 ≤ 200. The new method can predict the overall micro/mini-channel database accurately on the whole. It can predict almost 95.5% of the non-aqueous data and 93.5% of the water data within the ± 30% error band.

This content is only available via PDF.
You do not currently have access to this content.