An experimental study on fluid flow and heat transfer in a multiport minichannel flat tube with micro-fin structures

This paper aims to investigate experimentally the heat transfer and flow characteristics of a multiport minichannel flat tube (MMFT) with a kind of axially continuous sawtoothed (two-dimensional) fin structure. The experiments using MMFTs with fourteen types micro-fin structures as test sections and water as working fluid were performed to study the effects of fin structure elements on heat transfer and pressure drop, including the height of fin (Hf), the bottom width of fin (Wf), the distance between two neighboring fins (S1) and the number of fins in a channel (N). The friction factor and Nusselt number of all samples have been obtained with Reynolds number ranging from 128 to 5645. The experimental data show that Nu and f both increase with the increase of Hf and N, and decrease with the increase of Wf. Moreover, as Hf, Wf and N remain the same, Nu has no obvious change with the increase of S1. More discussions on effect of fin have been performed in this work. The performance evaluation criterion (PEC) was calculated to comprehensively assess the performance of the MMFT with fins. The maximum value of PEC can reach 1.95 in the present study. Finally, based on experimental data, two new correlations of Nu and f are proposed.