Study on heat transfer and flow instability in open microchannels

doi:10.11949/0438-1157.20250304

Abstract

Abstract:

The flow boiling heat transfer characteristics of deionized water in open microchannels and smooth copper surfaces were studied. The boiling curves, heat transfer coefficient and pressure drop characteristics were obtained at different mass fluxes. The results show that at three mass flow rates, the critical heat flux and heat transfer coefficient of the open microchannel are generally higher than those of the smooth copper surface, while the average pressure drop characteristics are the opposite. Moreover, the open microchannel can improve the backflow phenomenon to a certain extent, thus reducing the wall temperature. Although the average pressure drop of the open microchannel is 23.6%—43.3% higher than that of the smooth copper surface, the average inlet pressure standard deviation is 54.0%—62.5% lower than that of the smooth copper surface, and the flow instability of the open microchannel can be greatly alleviated by reducing the mass flux compared with the smooth copper surface.

Key words: open microchannel, flow boiling, heat flux, pressure drop, flow instability

摘要：

研究了去离子水在开放微通道和光滑铜表面的流动沸腾换热特性，得到了不同质量流速下的沸腾曲线、传热系数、压降特性和压力标准差等曲线。结果表明，在三种质量流速下，开放微通道的临界热通量和传热系数整体高于光滑铜表面，而平均压降特性则相反。此外，开放微通道可以在一定程度上改善回流现象，从而降低通道壁面温度。尽管开放微通道的平均压降比光滑铜表面高23.6%~43.3%，但其平均进口压力标准偏差比光滑铜表面低54.0%~62.5%，且与光滑铜表面相比，减小质量流速可更大幅度地缓解开放微通道的流动不稳定性。

关键词: 开放微通道, 流动沸腾, 热通量, 压降, 流动不稳定性

CLC Number:

TK 124

Xiaoyu TANG, Qiang XU, Haoyuan YU, Chenyu PEI, Liejin GUO. Study on heat transfer and flow instability in open microchannels[J]. CIESC Journal, 2025, 76(11): 5687-5696.

唐晓宇, 徐强, 余昊远, 裴晨宇, 郭烈锦. 开放微通道中的换热及流动不稳定性研究[J]. 化工学报, 2025, 76(11): 5687-5696.

Figures/Tables 7

Fig.1 Schematic diagram of the experimental system

Fig.2 Schematic diagram of the test section: (a) test section explosion view; (b) internal structure of the heating copper block; (c) dimensions of flow section for open microchannels and smooth surfaces

Fig.3 Boiling curves of the open microchannel and the smooth copper surface at different mass fluxes

Fig.4 Heat transfer coefficient curves of the open microchannel and the smooth copper surface at different mass fluxes

Fig.5 Axial distribution of wall temperature of the open microchannel and the smooth copper surface at mass flux of 200 kg/(m2·s)

Fig.6 Variations of pressure drop with heat flux and exit vapor quality at different mass fluxes

Fig.7 Standard deviation of inlet and outlet pressure under different mass fluxes

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