本研究針對磁熱泵浦概念設計新型微型泵浦進行性能分析，利用溫度敏感磁性流體升溫後磁化強度會下降的特性，使對稱磁場兩側所受的磁體積力不平衡形成一淨驅動力推動流體。實驗會於流道中擺放釹鐵硼磁鐵提供穩定磁場，並透過加熱使流體於封閉迴路內產生自主流動，接著會針對單獨一組磁熱泵浦與串聯兩組磁熱泵浦進行性能分析。在單一磁熱泵浦中，會比較有無放置致冷晶片作為熱沉對於性能表現的影響，並在固定流道高度為350 μm的條件下針對不同熱通量進行流率與溫度量測。由結果可發現流率會隨著熱通量提高而增加，在置入一驅動電壓為5 V的致冷晶片後則可發現流道內整體溫度下修、冷熱端溫差亦有增大的趨勢，流率進而增加。後續進一步改變裝置管長的長度檢視其影響，可發現隨著管長由62 cm增至74 cm，因管壁摩擦力增加，流率隨之下降。本實驗架設下的單一磁熱泵浦最高流率約為88.76 μL/min(Re=1.00)。串聯磁熱泵浦則會於單獨一組磁熱泵浦中再串接第二組磁熱泵浦，以達到增加流率的目的，由結果可以發現流率有進一步提升的效果，因隨著串聯增加的磁驅動壓力，在熱通量為459.8 kW/m2下，達到最高的流率118.17 μL/min(Re=1.34)，不過串聯的效益會隨著熱通量的增加而下降。從溫度上來看，串聯磁熱泵浦因流率提升，帶熱與換熱變快的效果使流道內整體溫度相比於單一磁熱泵浦有下降的趨勢。利用溫度量測的結果可以進行磁體積力與磁驅動壓力的計算，由計算結果可以發現磁驅動壓力會隨著熱通量的提高而增加，置入致冷晶片同樣也有增加磁驅動壓力的效果；而在增加單一磁熱泵浦的管長後，磁驅動壓力有下降的趨勢。串聯磁熱泵浦在置入第二組磁熱泵浦後，磁驅動壓力有顯著增加的效果，流率因而增加。本研究計算出的磁驅動壓力約為30~130 Pa，與管流理論推出的120~450 Pa有不小的落差，主要因無法量測到流體實際的溫度，於壓克力上插熱電偶量測到的溫度與溫差低於實際的溫度。
本研究最後以COMSOL Multiphysics 5.6進行磁熱泵浦的模擬，雖然定量上與實驗有一定的差異，但趨勢上趨於一致。由模擬的結果同樣可發現到置入致冷晶片與串聯磁熱泵浦皆能使流率有所提升，連帶使流道內流體的溫度下降。另外也由模擬檢視插在壓克力上的熱電偶會低估流道內流體溫度的問題。

This study aims to design and analyze the performance of the thermomagnetic micropumps. The thermomagnetic micropumps drive the flow by a net driving force introduced by the unbalanced magnetic body force on both sides of magnetic field due to the decrease of magnetization while the temperature-sensitive magnetic fluid experiencing the increase of temperature. For the experiment, two Neodymium magnets were placed on both sides of the microchannel device as the source of magnetic field, and the fluid started to move as self-circulating in the closed-loop upon heating. The performance of single thermomagnetic pump and two thermomagnetic pumps in serial connection were analyzed. In the experiment of single magnetic pump, the influence on the performance of with or without a cooling device as a heat sink was compared. The flow rates and temperature variations were measured for different heat flux conditions in a microchannel with height of 350 μm. The results showed that the flow rates increased as the heat flux increased. After adding a cooling chip with the applying voltage of 5 V, it was observed that the overall temperature in the microchannel reduced. Additionally, the increase of the temperature difference between the cold and hot sides caused greater flow rate. The total pipe length in the closed-loop was changed to examine its influence. It could be found that as the tube length increased from 62 cm to 74 cm, the flow rate decreased due to the increase of surface friction in tubes. The maximum flow rate of the single thermomagnetic pump was about 88.76 μL/min (Re=1.00) in current experimental setup. To further increase the flow rate, two thermomagnetic pumps were connected in series connection. The result showed that the flow rate had improved because the magnetic driving force increased with the series connection. The maximum flow rate was increased to118.17 μL/min(Re=1.34) with a heat flux of 459.8 kW/m2; nevertheless, the efficiency of the serial connection thermomagnetic pump decreased as the heat flux increased. The increase of the flow rate led to the rapid heat exchange, and made the overall temperature in the microchannel drop compared with the single thermomagnetic pump. The temperature results were later used for calculating the magnetic body force and the magnetic driving force. The calculation showed that the magnetic driving force increased with the increase of heat flux, and the same effect could be achieved by adding a cooling chip. However, the magnetic driving force tended to decrease after increasing the tube length of the single thermomagnetic pump. After connecting two thermomagnetic pumps in series connection, the magnetic driving force has a significant increment and the flow rate increased. The magnetic driving force was around 30~130 Pa calculated but they were different from the pressure values of 120~450 Pa estimated from the pipe flow theory. This is due to the exact temperature data could not be measured by only inserting thermocouples into the acrylic substrate, which will introduce the temperature difference between the cold and hot sides and the measured values from the thermocouple would be lower than the exact temperature in the microchannel.
The simulations were performed with COMSOL Multiphysics 5.6. Although difference between the simulation results and the experiment results have been noted during comparison, the trend of simulations results were in good agreement with experiments results in qualitative analysis. From the simulation results, it could be found that the flow rate had a further improvement by adding a cooling chip or connecting two thermomagnetic pumps in series connection, forcing the overall temperature in the microchannel to reduce. In addition, it was examined that inserting thermocouples into the acrylic would highly underestimate the temperature of the fluid in the microchannel.

參考文獻

[1] R. E. Rosensweig, Ferrohydrodynamics. Courier Corporation, 2013.
[2] P. Phong, P. Nam, D. Manh, and I.-J. Lee, "Mn0. 5Zn0. 5Fe2O4 nanoparticles with high intrinsic loss power for hyperthermia therapy," Journal of Magnetism and Magnetic Materials, vol. 433, pp. 76-83, 2017.
[3] L. Phor and V. Kumar, "Self-cooling device based on thermomagnetic effect of MnxZn1− xFe2O4 (x= 0.3, 0.4, 0.5, 0.6, 0.7)/ferrofluid," Journal of Materials Science: Materials in Electronics, vol. 30, no. 10, pp. 9322-9333, 2019.
[4] R. Arulmurugan, G. Vaidyanathan, S. Sendhilnathan, and B. Jeyadevan, "Preparation and properties of temperature-sensitive magnetic fluid having Co0. 5Zn0. 5Fe2O4 and Mn0. 5Zn0. 5Fe2O4 nanoparticles," Physica B: Condensed Matter, vol. 368, no. 1-4, pp. 223-230, 2005.
[5] R. Hao, H. Liu, F. Xing, and J. Ma, "Study on developing application fields of micro differential pressure sensor with magnetic fluid," in Journal of Physics: Conference Series, 2020, vol. 1550, no. 4: IOP Publishing, p. 042010.
[6] H. Yamaguchi, Engineering fluid mechanics. Springer Science & Business Media, 2008.
[7] J. G. Gutierrez and M. Riccetti, "Analysis and Development of a Magnetocaloric Pump for Electronic Cooling Applications Using a Mn-Zn Ferrite Ferrofluid," in ASME International Mechanical Engineering Congress and Exposition, 2008, vol. 48746, pp. 631-636.
[8] M. Bahiraei and M. Hangi, "Automatic cooling by means of thermomagnetic phenomenon of magnetic nanofluid in a toroidal loop," Applied Thermal Engineering, vol. 107, pp. 700-708, 2016.
[9] M. Bahiraei and M. Hangi, "Investigating the effect of line dipole magnetic field on hydrothermal characteristics of a temperature-sensitive magnetic nanofluid using two-phase simulation," Nanoscale research letters, vol. 11, no. 1, p. 443, 2016.
[10] Y. Xuan, Q. Li, and M. Ye, "Investigations of convective heat transfer in ferrofluid microflows using lattice-Boltzmann approach," International Journal of Thermal Sciences, vol. 46, no. 2, pp. 105-111, 2007.
[11] K. Fumoto, H. Yamagishi, and M. Ikegawa, "A mini heat transport device based on thermo-sensitive magnetic fluid," Nanoscale and Microscale Thermophysical Engineering, vol. 11, no. 1-2, pp. 201-210, 2007.
[12] W. Lian, Y. Xuan, and Q. Li, "Characterization of miniature automatic energy transport devices based on the thermomagnetic effect," Energy Conversion and Management, vol. 50, no. 1, pp. 35-42, 2009.
[13] V. Chaudhary, Z. Wang, A. Ray, I. Sridhar, and R. Ramanujan, "Self pumping magnetic cooling," Journal of Physics D: Applied Physics, vol. 50, no. 3, p. 03LT03, 2016.
[14] M. Petit, Y. Avenas, A. Kedous-Lebouc, W. Cherief, and E. Rullière, "Experimental study of a static system based on a magneto-thermal coupling in ferrofluids," International journal of refrigeration, vol. 37, pp. 201-208, 2014.
[15] Y. Iwamoto, H. Nakasumi, Y. Ido, and H. Yamaguchi, "Long-distance heat transport based on temperature-dependent magnetization of magnetic fluids," International Journal of Applied Electromagnetics and Mechanics, no. Preprint, pp. 1-14, 2020.
[16] C.-C. Yang, "The Application and Measurement of the Temperature-Sensitive Magnetic Fluid in Magnetocaloric Pump ", Master, Power Mechanical Engineering, National Tsing Hua University, 2019.
[17] Y. Iwamoto, Y. Fuji, K. Takeda, X.-D. Niu, and H. Yamaguchi, "Application of a Binary Temperature-Sensitive Magnetic Fluid for a Mini Magnetically-Driven Heat Transport Device," Journal of the Japanese Society for Experimental Mechanics, vol. 13, no. Special_Issue, pp. s18-s23, 2013.
[18] H. Yamaguchi and Y. Iwamoto, "Energy transport in cooling device by magnetic fluid," Journal of Magnetism and Magnetic Materials, vol. 431, pp. 229-236, 2017.
[19] J. G. Smits, "Piezoelectric micropump with three valves working peristaltically," Sensors and Actuators A: Physical, vol. 21, no. 1-3, pp. 203-206, 1990.
[20] F. Van de Pol, H. Van Lintel, M. Elwenspoek, and J. Fluitman, "A thermopneumatic micropump based on micro-engineering techniques," Sensors and Actuators A: Physical, vol. 21, no. 1-3, pp. 198-202, 1990.
[21] R. Zengerle, A. Richter, and H. Sandmaier, "A micro membrane pump with electrostatic actuation," in [1992] Proceedings IEEE Micro Electro Mechanical Systems, 1992: IEEE, pp. 19-24.
[22] W. L. Benard, H. Kahn, A. H. Heuer, and M. A. Huff, "Thin-film shape-memory alloy actuated micropumps," Journal of Microelectromechanical systems, vol. 7, no. 2, pp. 245-251, 1998.
[23] A. Olsson, O. Larsson, J. Holm, L. Lundbladh, O. Öhman, and G. Stemme, "Valve-less diffuser micropumps fabricated using thermoplastic replication," Sensors and Actuators A: Physical, vol. 64, no. 1, pp. 63-68, 1998.
[24] C. Zhi, T. Shinshi, and M. Uehara, "A micro pump driven by a thin film permanent magnet," Journal of Advanced Mechanical Design, Systems, and Manufacturing, vol. 6, no. 7, pp. 1180-1189, 2012.
[25] K. Handique, D. Burke, C. Mastrangelo, and M. Burns, "On-chip thermopneumatic pressure for discrete drop pumping," Analytical Chemistry, vol. 73, no. 8, pp. 1831-1838, 2001.
[26] C. G. Cooney and B. C. Towe, "A thermopneumatic dispensing micropump," Sensors and Actuators A: Physical, vol. 116, no. 3, pp. 519-524, 2004.
[27] P. S. Chee, M. N. Minjal, P. L. Leow, and M. S. M. Ali, "Wireless powered thermo-pneumatic micropump using frequency-controlled heater," Sensors and Actuators A: Physical, vol. 233, pp. 1-8, 2015.
[28] S. Lee, S. Y. Yee, A. Besharatian, H. Kim, L. P. Bernal, and K. Najafi, "Adaptive gas pumping by controlled timing of active microvalves in peristaltic micropumps," in TRANSDUCERS 2009-2009 International Solid-State Sensors, Actuators and Microsystems Conference, 2009: IEEE, pp. 2294-2297.
[29] J. Gao, D. Guo, S. Santhanam, and G. Fedder, "Large stroke electrostatic actuated PDMS-on-silicon micro-pump," in 2015 Transducers-2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2015: IEEE, pp. 117-120.
[30] I. Lee, P. Hong, C. Cho, B. Lee, K. Chun, and B. Kim, "Four-electrode micropump with peristaltic motion," Sensors and Actuators A: Physical, vol. 245, pp. 19-25, 2016.
[31] X. Sun, Y. Hao, S. Guo, X. Ye, and X. Yan, "The development of a new type of compound peristaltic micropump," in 2008 IEEE International Conference on Robotics and Biomimetics, 2009: IEEE, pp. 698-702.
[32] F. Sassa, Y. Al-Zain, T. Ginoza, S. Miyazaki, and H. Suzuki, "Miniaturized shape memory alloy pumps for stepping microfluidic transport," Sensors and Actuators B: Chemical, vol. 165, no. 1, pp. 157-163, 2012.
[33] A. Saren, A. Smith, and K. Ullakko, "Integratable magnetic shape memory micropump for high-pressure, precision microfluidic applications," Microfluidics and Nanofluidics, vol. 22, no. 4, pp. 1-10, 2018.
[34] N.-T. Nguyen and X. Huang, "Miniature valveless pumps based on printed circuit board technique," Sensors and Actuators A: Physical, vol. 88, no. 2, pp. 104-111, 2001.
[35] W. Wang, Y. Zhang, L. Tian, X. Chen, and X. Liu, "Piezoelectric diffuser/nozzle micropump with double pump chambers," Frontiers of Mechanical Engineering in China, vol. 3, no. 4, pp. 449-453, 2008.
[36] R. Kant, D. Singh, and S. Bhattacharya, "Digitally controlled portable micropump for transport of live micro-organisms," Sensors and Actuators A: Physical, vol. 265, pp. 138-151, 2017.
[37] W. Lian, Y. Xuan, and Q. Li, "Investigation on Multi-Pump Liquid-Cooling Loop Based on Thermomagnetic Effect," in International Heat Transfer Conference, 2010, vol. 49385, pp. 417-423.
[38] Microchem, "SU-8 2000 Permanent Epoxy Negative Photoresist PROCESSING GUIDELINES FOR:SU-8 2025, SU-8 2035, SU-8 2050 and SU-8 2075," ed, 2005.
[39] W. W. Y. Chow, K. F. Lei, G. Shi, W. J. Li, and Q. Huang, "Microfluidic channel fabrication by PDMS-interface bonding," Smart materials and structures, vol. 15, no. 1, p. S112, 2005.
[40] Microchem, "LOR Lift-Off Resists," ed, 2016.
[41] Shipley, "MICROPOSIT S1800 SERIES PHOTO RESISTS," ed, 2016.
[42] Y. Xuan and W. Lian, "Electronic cooling using an automatic energy transport device based on thermomagnetic effect," Applied Thermal Engineering, vol. 31, no. 8-9, pp. 1487-1494, 2011.