本實驗研究探討具平行/漸擴毫米流道熱沉內相變化材料微膠囊懸浮液強制對流冷卻特性，本實驗使用相變化微膠囊顆粒之核心材料為正二十烷，外殼材料為尿素甲醛樹酯，其粒徑分布為5-15 μm。本實驗之毫米流道熱沉為無氧銅材料，流道總長為50 mm、流道總寬為25.1 mm。在平行流道中，單一流道截面積尺寸為寬1 mm、高1.5 mm；在漸擴流道(β=1.38˚、β=2.06˚)入口中，其單一流道截面積尺寸與平行流道相同；在漸擴流道(β=1.38˚)出口中，單一流道截面積尺寸為寬2.2 mm、高1.5 mm；在漸擴流道(β=2.06˚)出口中，單一流道截面積尺寸為寬2.8 mm、高1.5 mm。本實驗研究相關參數範圍：相變化微膠囊懸浮液重量百分濃度分別為2%、5%、10%，換算成相變化材料百分濃度分別為1.02%、2.53%、3.77%；體積流量為100 cm³/min、180 cm³/min、300 cm³/min、420 cm³/min、600 cm³/min；流道底部加熱熱通量為3.2 W/cm²、4 W/cm²、4.8 W/cm²。由本實驗結果顯示，添加相變化微膠囊顆粒確實有降低壁溫的效果，且能提升平均熱傳增益，其最大增益可達22.3%；隨著漸擴流道的角度增大，仍然有提升平均熱傳增益的效果，但其增加的幅度有下降的趨勢。

A comparative study was experimentally undertaken to explore the convective cooling characteristics of water-based microencapsulated phase change material (MEPCM) suspension flow through one parallel and two divergent mini-channel heat sinks. The MEPCM particles used for the water-based suspensions were fabricated in the laboratory characterized with their diameters in the range of 5-15 μm. The MEPCM are manufacturing by interfacial polycondensation, using n-eicosane as a core material and urea-melamine-formaldehyde as a shell material. The multi-channel heat sinks of a length of 50 mm and a width of 25.1 mm were fabricated of oxygen-free copper with eight parallel or divergent mini-channels, each with an inlet cross-section of 1 mm in width and 1.5 mm in height. The divergent mini-channel heat sinks were characterized with their width linearly expanded, respectively, from the inlet with a divergence angle of β= 1.38˚ and 2.06˚. The pertinent experimental conditions considered are in the following ranges: the volumetric flow rate of working fluid through the heat sinks Q= 100, 180, 300, 420, 600 cm³⁄min; and the heat flux imposed over the bottom of the heat sink, q= 3.2, 4, 4.8 W⁄cm²; the mass fraction of MEPCM dispersed in the suspension flow, ω_mepcm= 2%, 5%, and 10%; ω_pcm= 1.02%, 2.35%, and 3.77%; the inlet temperature of the suspension flow, T_in=34±0.2˚C. The resulting ranges of the dimensionless parameters to the present problem are: the Reynolds number, Re= 238-1375; the Peclet number, Pe= 1100-6665; the modified Stefan number, Ste= 0.016-0.147; and the inlet subcooling parameter, Sb= 0.188-0.159. The experimental results clearly reveal that using the MEPCM suspension to replace the pure water as the coolant through the mini-channel heat sinks under high values of latent-sensible heat ratio conditions can give rise to an enhancement of 22.3%, 17%, and 7.1%, respectively, in the average heat transfer coefficient for the parallel and divergent (β= 1.38˚, 2.06˚) mini-channel heat sinks.

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