Review and Comparative Analysis of Studies on Saturated Flow Boiling in Small Channels

Abstract

Recent studies relating to saturated flow boiling in minichannels and microchannels are reviewed, with a focus on the functional dependence of the heat transfer characteristics on thermodynamic vapor quality. While there is general agreement in the literature that the heat transfer coefficient increases with increases in heat flux, conflicting trends have been reported on the influence of vapor quality. A compilation and analysis of the results from recent investigations in the literature on flow boiling in small channels is presented.Further, correlations for flow boiling proposed in these studies are quantitatively assessed by comparing them against ten independent data sets from the published literature covering a range of hydraulic diameters from 0.16 to 2.01 mm. Recommended topics for future research in this field are also identified.

A composite heat transfer correlation for saturated flow boiling in small channels

“…It was also noted in [1] that most of the existing minichannel and microchannel heat transfer correlations were developed based on small data sets [13][14][15][16][17][18][19][20]. As a result, these correlations usually performed well in the parameter range over which they were fit, but did not extrapolate well beyond their often narrow operating range [1]. One of the only correlations that was based on a larger set of minichannel and microchannel heat transfer measurements from several independent sources was due to Thome et al [21,22].…”

“…Heat transfer in minichannels and microchannels has received significant attention over the last few years, especially for application to electronics cooling [1][2][3][4][5][6]. While single-phase flow in small channels can easily be described with equations developed for conventional-sized tubes, microchannel flow boiling is significantly affected by the confinement of bubbles [7][8][9][10].…”

“…Existing heat transfer correlations are unable to accurately predict the flow boiling heat transfer coefficient in small channels over a wide range of operating parameters [1,4,11] as the heat transfer mechanisms are not fully understood. A recent review of the literature [1] showed that a pool boiling correlation [12] outperforms dedicated flow boiling correlations when applied to a large database of results from different research groups for channels of hydraulic diameters smaller than 2 mm.…”

“…However, even the best predictions showed a mean absolute error (MAE) of 40% against the large experimental database, and predicted less than half of the measured data to within a deviation of ±30%. It was also noted in [1] that most of the existing minichannel and microchannel heat transfer correlations were developed based on small data sets [13][14][15][16][17][18][19][20]. As a result, these correlations usually performed well in the parameter range over which they were fit, but did not extrapolate well beyond their often narrow operating range [1].…”

“…A recent review of the literature [1] showed that a pool boiling correlation [12] outperforms dedicated flow boiling correlations when applied to a large database of results from different research groups for channels of hydraulic diameters smaller than 2 mm. However, even the best predictions showed a mean absolute error (MAE) of 40% against the large experimental database, and predicted less than half of the measured data to within a deviation of ±30%.…”