Development of two-phase flow microchannel heat sink applied to solar-tracking high-concentration photovoltaic thermal hybrid system
Development of two-phase flow microchannel heat sink applied to solar-tracking high-concentration photovoltaic thermal hybrid system
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DOI：
10.1016/j.energy.2020.118739
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发表时间：
2020-12
期刊：
影响因子：
9
通讯作者：
Sihui Hong;Bohan Zhang;C. Dang;E. Hihara
中科院分区：
文献类型：
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作者：
Sihui Hong;Bohan Zhang;C. Dang;E. Hihara
为了提高聚光光伏（CPV）系统的能量转换效率，本研究提出了一种高聚光光伏热（HCPVT）混合系统。该系统将聚光光伏发电的功能从简单的发电扩展到同时提供电力和热能。因此，利用废热（否则会损失到环境中）可以提高整体系统效率并提高发电输出的经济价值。然而，鉴于工作温度对太阳能电池的光伏效率和寿命的显着影响，太阳跟踪过程中光伏组件的高效冷却已成为HCPVT混合系统发展的巨大挑战。在目前的工作中，提出了一种采用两相流沸腾的径向膨胀微通道散热器（REMHS），以实现冷却太阳能电池和从回收的热量产生蒸汽的双重目标。径向扩展的微通道被设计成促进自发蒸汽去除，同时减轻由于装置方向的变化而产生的流动分布不均。通过进行去离子水的流动沸腾试验，研究了所提出的REMHS在不同取向角下的传热特性。随着微通道的取向角从0°增加到45°，REMHS的局部传热系数增加了32%，然后随着取向角的进一步增加保持稳定。此外，REMHS的传热能力表现出对热通量的强烈依赖性，与流量的相关性较弱，这是蒸发液膜传热的典型特征。此外，通过在1070个太阳的聚光比下进行室外实时太阳跟踪测试，发现所提出的REMHS在高聚光太阳能下保持了优越的流动沸腾性能。电池表面最高表面温度保持在110°C以下，观察到的最大温差低于5°C。
To enhance the energy conversion efficiency of a concentration photovoltaic (CPV) system, a high-concentration photovoltaic thermal (HCPVT) hybrid system is proposed in this study. This system extends the functionality of the CPV from simply generating electricity to simultaneously providing electricity and heat. Thus, the utilization of the exhaust heat, which would otherwise be lost to the environment, could enhance the overall system efficiency and boost the economic value of the generated power output. However, in view of the significant influence of the operating temperature on the photovoltaic efficiency and longevity of the solar cells, an efficient cooling of the photovoltaic module during the solar-tracking process has become a great challenge to the development of HCPVT hybrid systems. In the present work, a radially expanding microchannel heat sink (REMHS) employing two-phase flow boiling is proposed to achieve the twin objectives of cooling the solar cells and generating steam from the recovered heat. The radially expanding microchannels are designed to facilitate a spontaneous vapor removal while alleviating flow maldistribution arising due to the changes in orientation of the device. By conducting flow boiling tests of deionized water, the heat transfer characteristics of the proposed REMHS under various orientation angles were investigated. The local heat transfer coefficient of the REMHS increased by 32%, as the orientation angle of the microchannels increased from 0° to 45°, and then remained steady with any further increase in the orientation angle. In addition, the heat transfer capability of the REMHS exhibited a strong dependence on the heat flux and was weakly correlated with the flow rate, which is typical of an evaporation liquid film heat transfer. Additionally, by conducting outdoor real-time sun tracking tests under a concentration ratio of 1070 suns, it was found that the proposed REMHS maintained a superior flow boiling performance under a high-concentration solar energy. The highest surface temperature on the cell surface remained below 110°C and the observed maximum temperature difference was below 5°C.