本論文以實驗量測的方式探討毫/微米流道疊置雙層熱沉與單層微米流道熱沉之熱傳増益與壓降降幅，並在毫米流道及微米流道通入純水或奈米相變化乳液，重量百分濃度有4.77%及9.04%兩種。毫/微米流道疊置雙層熱沉是由單層微米流道熱沉上疊置一毫米流道熱沉所組成，利用此毫米流道達到比單層微米流道熱沉更低之壓降及更高之熱傳效益。毫米流道及微米流道皆以無氧銅線切割加工而成，兩流道總寬度為18mm，總長度為40mm，其中毫米流道熱沉有18條長度40mm、寬度0.7mm、高度2.8mm的矩形流道，水力直徑為1.12mm，微米流道熱沉有36條長度40mm、寬度0.25mm、高度1.0mm的矩形流道，水力直徑為0.40mm。實驗控制條件則有入口溫度、流體帶走之有效熱通量及流量，單層微米流道熱沉及毫/微米流道疊置雙層熱沉入口溫度皆控制入口溫度為34℃，而流體帶走之有效熱通量則皆為 、 及 三種，其中加熱面積為7.2 ，單層微米流道熱沉之雷諾數範圍則是408.46~1231.4之間，毫/微米流道疊置雙層熱沉則以與單層微米流道熱沉相同之總流量以不同比例通入，流量比分別為0.50、1.00、1.40、2.00、3.00及3.92。由熱傳實驗結果可知，在都通入純水的情況下，毫/微米流道疊置雙層熱沉與單層微米流道熱沉相比，壓降大幅壓抑了95%，在熱傳増益方面，毫/微米流道疊置雙層熱沉中通入(純水/奈米相變化乳液 )時，與單層微米流道熱沉通入純水相比平均紐賽數最大增益了112.4%，從上述實驗結果可知毫/微米流道疊置雙層熱沉與單層微米流道熱沉相比，確實能同時達到降低壓降及提高熱傳増益之效果。

In the present study, an experimental study was performed to investigate the cooling performance of a mini- and micro-channel stacked double-layer heat sink with water/nano-PCM emulsion as the coolants. The mini- and micro-channel stacked double-layer heat sink is composed of a single-layer microchannel heat sink stacked with a minichannel heat sink.Compared with a single-layer microchannel heat sink, the design can effectively reduce the pressure drop and increase the heat transfer efficacy.The minichannel heat sink and the microchannel heat sink were fabricated from oxygen-free copper. The total width of the two channels is 18mm, and the total length is 40mm. The minichannel heat sink has 18 rectangular channels with a length of 40mm, a width of 0.7mm, and a height of 2.8mm, it has a hydraulic diameter of 1.12mm. The microchannel heat sink has 36 rectangular channels with a length of 40mm, a width of 0.25mm, and a height of 1.0mm, it has a hydraulic diameter of 0.40mm. The mass fractions of the nano-PCM emulsion was 4.77% and 9.04%. The experimental operating condition such as the following: the range of the Reynolds number of the single-layer microchannel heat sink from 408.46 to 1231.40, the actual heat flux applied at microchannel heat sink =8.78,17.10,26.16 , the inlet fluid temperature is near 34℃. The ratio of flow rate is upper channel to lower channel = 0.50, 1.00, 1.40, 2.00, 3.00, and 3.92, respectively. And the total flow rate of the mini- and micro-channel stacked double-layer heat sink is the same as the single-layer microchannel heat sink.
The experimental results reveal that the thermal and hydraulic performance of the mini- and micro-channel stacked double-layer heat sink can be enhanced as compared to the single-layer microchannel heat sink. For instance, compared to the single-layer microchannel heat sink, the pressure drop of the mini- and micro-channel stacked double-layer heat sink at the same working fluid(pure water) is found to be reduced by 95% at Re=643.74. When the nano-PCM emulsion replace the pure water as the working fluid in a microchannel, the average Nusselt number of the mini- and micro-channel stacked double-layer heat sink is found to be enhanced by 112.4% at Re=1114.88.

[1] D. B. Tuckerman and R. F. W. Pease, "HIGH-PERFORMANCE HEAT SINKING FOR VLSI," Electron Device Letters, vol. 2, no. 5, pp. 126-129, 1981, doi: 10.1109/edl.1981.25367.
[2] S. G. Kandlikar et al., "Heat Transfer in Microchannels—2012 Status and Research Needs," Journal of Heat Transfer, vol. 135, no. 9, 2013, doi: 10.1115/1.4024354.
[3] W. Qu and I. Mudawar, "<Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink.pdf>," International Journal of Heat and Mass Transfer, vol. 45, pp. 2549-2565, 2001.
[4] P. Gunnasegaran, H. A. Mohammed, N. H. Shuaib, and R. Saidur, "The effect of geometrical parameters on heat transfer characteristics of microchannels heat sink with different shapes," International Communications in Heat and Mass Transfer, vol. 37, no. 8, pp. 1078-1086, 2010, doi: 10.1016/j.icheatmasstransfer.2010.06.014.
[5] M. Q. Ansari and G. Zhou, "Influence of structured surface roughness peaks on flow and heat transfer performances of micro- and mini-channels," International Communications in Heat and Mass Transfer, vol. 110, 2020, doi: 10.1016/j.icheatmasstransfer.2019.104428.
[6] S. G.Kandlikar, "<Characterization of Surface Roughness Effects on Pressure Drop in Single-phase.pdf>," pp. 1-57, 2004.
[7] P.-S. Lee and S. V. Garimella, "Thermally developing flow and heat transfer in rectangular microchannels of different aspect ratios," International Journal of Heat and Mass Transfer, vol. 49, no. 17-18, pp. 3060-3067, 2006, doi: 10.1016/j.ijheatmasstransfer.2006.02.011.
[8] H. Yun, B. Chen, and B. Chen, "Numerical Simulation of Geometrical Effects on the Liquid Flow and Heat Transfer in Smooth Rectangular Microchannels," International Conference on Micro/Nanoscale Heat Transfer, vol. 3, pp. 271-277, 2010, doi: 10.1115/MNHMT2009-18413.
[9] X.-D. Wang, A. Bin, and J.-L. Xu, "Optimal geometric structure for nanofluid-cooled microchannel heat sink under various constraint conditions," Energy Conversion and Management, vol. 65, pp. 528-538, 2013, doi: 10.1016/j.enconman.2012.08.018.
[10] Z. Feng, X. Ai, P. Wu, Q. Lin, and Z. Huang, "Experimental investigation of laminar flow and heat transfer characteristics in square minichannels with twisted tapes," International Journal of Heat and Mass Transfer, vol. 158, 2020, doi: 10.1016/j.ijheatmasstransfer.2020.119947.
[11] C. J. Ho, L. C. Wei, and Z. W. Li, "An experimental investigation of forced convective cooling performance of a microchannel heat sink with Al2O3/water nanofluid," Applied Thermal Engineering, vol. 30, no. 2-3, pp. 96-103, 2010, doi: 10.1016/j.applthermaleng.2009.07.003.
[12] A. M. Khudhair and M. M. Farid, "A review on energy conservation in building applications with thermal storage by latent heat using phase change materials," Energy Conversion and Management, vol. 45, no. 2, pp. 263-275, 2004, doi: 10.1016/s0196-8904(03)00131-6.
[13] I. Cerón, J. Neila, and M. Khayet, "Experimental tile with phase change materials (PCM) for building use," Energy and Buildings, vol. 43, no. 8, pp. 1869-1874, 2011, doi: 10.1016/j.enbuild.2011.03.031.
[14] S. Kuravi, K. M. Kota, J. Du, and L. C. Chow, "<Numerical Investigation of Flow and Heat Transfer Performance of Nano-Encapsulated Phase Change Material Slurry in Microchannels.pdf>," heat Transfer, vol. 131, pp. 062901-1-062901-9, 2009, doi: 10.1115/1.3084123兴.
[15] C. J. Ho, S.-T. Hsu, J.-H. Jang, S. F. Hosseini, and W.-M. Yan, "Experimental study on thermal performance of water-based nano-PCM emulsion flow in multichannel heat sinks with parallel and divergent rectangular mini-channels," International Journal of Heat and Mass Transfer, vol. 146, 2020, doi: 10.1016/j.ijheatmasstransfer.2019.118861.
[16] V. P. Gaikwad and S. P. More, "<CPU Processor Cooling by using Microchannel.pdf>," IJERT, vol. 6, no. 11, pp. 214-219, 2017.
[17] A. B. S. Alquaity, S. A. Al-Dini, E. N. Wang, and B. S. Yilbas, "Numerical investigation of liquid flow with phase change nanoparticles in microchannels," International Journal of Heat and Fluid Flow, vol. 38, pp. 159-167, 2012, doi: 10.1016/j.ijheatfluidflow.2012.10.001.
[18] R. Sabbah, M. M. Farid, and S. Al-Hallaj, "Micro-channel heat sink with slurry of water with micro-encapsulated phase change material: 3D-numerical study," Applied Thermal Engineering, vol. 29, no. 2-3, pp. 445-454, 2009, doi: 10.1016/j.applthermaleng.2008.03.027.
[19] L. Yang, J.-n. Huang, M. Mao, and W. Ji, "Numerical assessment of Ag-water nano-fluid flow in two new microchannel heatsinks: Thermal performance and thermodynamic considerations," International Communications in Heat and Mass Transfer, vol. 110, 2020, doi: 10.1016/j.icheatmasstransfer.2019.104415.
[20] K. Vafai and L. Zhu, "Analysis of two-layered micro-channel heat sink concept in electronic cooling," International Journal of Heat and Mass Transfer, vol. 42, no. 12, pp. 2287-2297, Jun 1999, doi: 10.1016/s0017-9310(98)00017-9.
[21] G. N. Xie, Y. Q. Liu, B. Sunden, and W. H. Zhang, "Computational Study and Optimization of Laminar Heat Transfer and Pressure Loss of Double-Layer Microchannels for Chip Liquid Cooling," (in English), J. Therm. Sci. Eng. Appl., Article vol. 5, no. 1, p. 9, Mar 2013, Art no. 011004, doi: 10.1115/1.4007778.
[22] J. M. Wu, J. Y. Zhao, and K. J. Tseng, "Parametric study on the performance of double-layered microchannels heat sink," Energy Conversion and Management, vol. 80, pp. 550-560, 2014, doi: 10.1016/j.enconman.2014.01.014.
[23] H. E. Ahmed, M. I. Ahmed, I. M. F. Seder, and B. H. Salman, "Experimental investigation for sequential triangular double-layered microchannel heat sink with nanofluids," International Communications in Heat and Mass Transfer, vol. 77, pp. 104-115, 2016, doi: 10.1016/j.icheatmasstransfer.2016.06.010.
[24] T. C. Hung, W. M. Yan, and W. P. Li, "Analysis of heat transfer characteristics of double-layered microchannel heat sink," (in English), International Journal of Heat and Mass Transfer, Article vol. 55, no. 11-12, pp. 3090-3099, May 2012, doi: 10.1016/j.ijheatmasstransfer.2012.02.038.
[25] B. Rajabifar, "Enhancement of the performance of a double layered microchannel heatsink using PCM slurry and nanofluid coolants," International Journal of Heat and Mass Transfer, vol. 88, pp. 627-635, 2015, doi: 10.1016/j.ijheatmasstransfer.2015.05.007.
[26] H. Shen, G. Xie, and C.-C. Wang, "The numerical simulation with staggered alternation locations and multi-flow directions on the thermal performance of double-layer microchannel heat sinks," Applied Thermal Engineering, vol. 163, 2019, doi: 10.1016/j.applthermaleng.2019.114332.
[27] A. Sakanova, S. Yin, J. Zhao, J. M. Wu, and K. C. Leong, "Optimization and comparison of double-layer and double-side micro-channel heat sinks with nanofluid for power electronics cooling," Applied Thermal Engineering, vol. 65, no. 1-2, pp. 124-134, 2014, doi: 10.1016/j.applthermaleng.2014.01.005.
[28] N. Patel and H. B. Mehta, "Experimental investigations on a variable channel width double layered minichannel heat sink," International Journal of Heat and Mass Transfer, vol. 165, 2021, doi: 10.1016/j.ijheatmasstransfer.2020.120633.
[29] 彭建凱, "毫/微米流道疊置雙層熱沉內分流水/氧化鋁奈米流體之強制對流熱散逸效能實驗研究," pp. 1-110, 2020, doi: 10.6844/NCKU202002563.
[30] C. O. Popiel and J. Wojtkowiak, "Simple Formulas for Thermophysical Properties of Liquid Water for Heat Transfer Calculations (from 0°C to 150°C)," Heat Transfer Engineering, vol. 19, no. 3, pp. 87-101, 1998, doi: 10.1080/01457639808939929.
[31] S. Shen, J. L. Xu, J. J. Zhou, and Y. Chen, "Flow and heat transfer in microchannels with rough wall surface," Energy Conversion and Management, vol. 47, no. 11-12, pp. 1311-1325, 2006, doi: 10.1016/j.enconman.2005.09.001.
[32] C.-J. Ho, W.-C. Chen, and W.-M. Yan, "Experimental study on cooling performance of minichannel heat sink using water-based MEPCM particles," International Communications in Heat and Mass Transfer, vol. 48, pp. 67-72, 2013, doi: 10.1016/j.icheatmasstransfer.2013.08.023.
[33] J. Lee and I. Mudawar, "Assessment of the effectiveness of nanofluids for single-phase and two-phase heat transfer in micro-channels," International Journal of Heat and Mass Transfer, vol. 50, no. 3-4, pp. 452-463, 2007, doi: 10.1016/j.ijheatmasstransfer.2006.08.001.
[34] M. E. Steinke and S. G. Kandlikar, "Single-phase liquid friction factors in microchannels," International Journal of Thermal Sciences, vol. 45, no. 11, pp. 1073-1083, 2006, doi: 10.1016/j.ijthermalsci.2006.01.016.
[35] B. Agostini, A. Bontemps, and B. Thonon, "Effects of Geometrical and Thermophysical Parameters on Heat Transfer Measurements in Small-Diameter Channels," Heat Transfer Engineering, vol. 27, no. 1, pp. 14-24, 2006, doi: 10.1080/01457630500341656.
[36] P.-S. Lee, S. V. Garimella, and D. Liu, "Investigation of heat transfer in rectangular microchannels," International Journal of Heat and Mass Transfer, vol. 48, no. 9, pp. 1688-1704, 2005, doi: 10.1016/j.ijheatmasstransfer.2004.11.019.
[37] Y. Rao, F. Dammel, and P. Stephan, "Experiments on the Cooling Performance of Microencapsulated Phase Change Material Suspension Flow in Rectangular," Heat Transfer Summer Conference pp. 923-929, 2009, doi: 10.1115/HT2007-32116.