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首页> 外文期刊>Journal of Heat Transfer >Probing the Local Heat Transfer Coefficient of Water-Cooled Microchannels Using Time-Domain Thermoreflectance
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Probing the Local Heat Transfer Coefficient of Water-Cooled Microchannels Using Time-Domain Thermoreflectance

机译：使用时域热反射法探测水冷微通道的局部传热系数

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摘要

The demands for increasingly smaller, more capable, and higher power density technologies have heightened the need for new methods to manage and characterize extreme heat fluxes. This work presents the use of an anisotropic version of the time-domain thermoreflectance (TDTR) technique to characterize the local heat transfer coefficient (HTC) of a water-cooled rectangular microchannel in a combined hot-spot heating and subcooled channel-flow configuration. Studies focused on room temperature, single-phase, degassed water flowing at an average velocity of 3.5 m/s in a 480 μm hydraulic diameter microchannel (e.g., Re 1850), where the TDTR pump heating laser induces a local heat flux of 900 W/cm2 in the center of the microchannel with a hot-spot area of 250 μm2. By using a differential TDTR measurement approach, we show that thermal effusivity distribution of the water coolant over the hot-spot is correlated to the single-phase convective heat transfer coefficient, where both the stagnant fluid (i.e., conduction and natural convection) and flowing fluid (i.e., forced convection) contributions are decoupled from each other. Our measurements of the local enhancement in the HTC over the hot-spot are in good agreement with established Nusselt number correlations. For example, our flow cooling results using a Ti metal wall support a maximum HTC enhancement via forced convection of 1060 ± 190 kW/m2 K, where the Nusselt number correlations predict 900 ± 150 kW/m2 K.
机译：对越来越小的，更强大的功能和更高的功率密度技术的需求，使得对管理和表征极端热通量的新方法的需求日益增加。这项工作提出了使用时域热反射（TDTR）技术的各向异性版本来表征热点结合加热和过冷通道流动配置中水冷矩形微通道的局部传热系数（HTC）。研究的重点是在480μm液压直径微通道（例如Re 1850）中以3.5 m / s的平均速度流动的室温，单相脱气水，其中TDTR泵加热激光器产生900 W的局部热通量/ cm2在微通道的中心，热点面积为250μm2。通过使用差分TDTR测量方法，我们表明热点上的水冷却剂的热效率分布与单相对流换热系数相关，在此情况下，滞流流体（即传导和自然对流）和流动流体（即，强迫对流）的贡献相互分离。我们对HTC在热点上局部增强的测量与已建立的Nusselt数相关性非常吻合。例如，我们使用钛金属壁的流动冷却结果通过强制对流1060±190 kW / m2 K达到了HTC的最大增强，其中努塞尔特数相关性预测为900±150 kW / m2K。

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  • 来源
    《Journal of Heat Transfer》 |2017年第11期|112403.1-112403.12|共12页
  • 作者

    Mehrvand Mehrdad; Putnam Shawn A.;

  • 作者单位

    Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States;

    Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
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