Experimental investigation on flow boiling characteristics of radial expanding minichannel heat sinks applied for two-phase flow inlet
Experimental investigation on flow boiling characteristics of radial expanding minichannel heat sinks applied for two-phase flow inlet
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DOI：
10.1016/j.ijheatmasstransfer.2020.119316
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发表时间：
2020-04
影响因子：
5.2
通讯作者：
Sihui Hong;C. Dang;E. Hihara
中科院分区：
文献类型：
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作者：
Sihui Hong;C. Dang;E. Hihara
常规微通道换热器一般不允许有两相流入口条件，要求有一定的过冷度以保证系统的高效运行。为解决多热源冷却问题，提出了一种利用去离子水流动沸腾的环形径向扩张微通道热沉。在入口蒸汽质量干度为0.01 ~ 0.53的范围内，研究了REMHS的流动沸腾换热特性。在低-中等质量流量（22-132 kg/m2 s）和中高热流密度（33.1-176.4 kW/m2）条件下，TP流入口下，REMHS中的主要流型为段塞-环形流和环形流。实验结果表明，在TP流入口下，所提出的REMHS保持了稳定的高流动沸腾传热性能，没有发生热劣化。当xin从0.04增加到0.53时，最大局部换热系数从42.5增加到51.9 kW/m2 K，增加了22%。在TP流入口条件下，膨胀通道阵列间的流量分配比较均匀，换热器的换热能力具有较好的对称性。在实验范围内，传热系数的最大偏差小于19%。将六种经典的流动沸腾传热关联式与实验结果进行了比较，Li & Wu的关联式对所有实验数据都有较好的预测效果，MAE为21.1%。此外，还考察了串联REMHS的热独立性，发现串联REMHS之间的相互传热影响很小，有望应用于多热源冷却。
Generally, two-phase (TP) flow inlet condition is not allowed for conventional microchannel heat exchangers, and a certain subcooled degree of liquid is strictly required to guarantee the efficient operation of system. To solve multi-heat sources cooling issue, a type of circular radial expanding minichannels heat sink (REMHS) utilizing flow boiling of deionized water is proposed in present work. Flow boiling heat transfer of REMHS is investigated with the inlet vapor mass qualities in the range of 0.01–0.53. Under TP flow inlet, slug-annular and annular flows are the main flow patterns observed in REMHS in this work, where the low-medium mass flux (22–132 kg/m2s) and medium-high heat flux (33.1–176.4 kW/m2) conditions are applied. The experimental results illustrate that the proposed REMHS under TP flow inlet maintains a stable and high flow boiling heat transfer performance without occurring heat deterioration. Whenxinincreases from 0.04 to 0.53, the maximum local heat transfer coefficient increases by 22% from 42.5 to 51.9 kW/m2K. The flow distribution among the expanding channel array is relatively uniform and the heat transfer capability in the REMHS displays a good symmetry under TP flow inlet. The maximum discrepancy in heat transfer coefficient is below 19% within our experimental range. Six classic flow boiling heat transfer correlations are compared with the experimental results, and Li & Wu's correlation gives a good prediction on all the measured data with MAE of 21.1%. Besides, the thermal independence of REMHS connected in series is also examined, and the mutual interaction in heat transfer between the REMHS in series is trivial, the proposed REMHS is expected to be applied to multi-heat source cooling.