本研究主要針對溫度敏感磁性流體在一般尺度與微尺度下的磁熱泵浦測試與量測，實驗設計利用溫度敏感磁性流體的磁化強度會因為溫度的上升而下降的原理，在流道中使用永久磁鐵施加高斯分布的磁場強度與熱源就能使溫度敏感磁性流體在流道中自主流動。在一般尺度下，利用改變磁鐵擺放位置找到當磁鐵中心位於加熱入口時會有最高的流率。後續也嘗試改變流道長度，連結的管長由1650 mm提高至3150 mm會發現流率跟著減少，這是因為隨著管長變長，造成流體與管壁間摩擦力增加。此外，也比較了在固定管長為1650 mm時三種熱通量與磁場強度下的流率，可發現流率會隨著磁場或熱通量變大而提高，流體反應時間則是隨之加快。流率最高在熱通量為8 kW/m^2與磁場Hx,max=136 kA/m下可達537.6 µL/min(Re=3.32)。在微尺度下，成功以熱壓印製程建造一個長寬分別為10、1 mm的壓克力微流道並加以磁場與熱源的自主驅動循環裝置。在本實驗中，量測4種流道高度(180、290、350、420 µm )在不同熱通量下的流率與溫度，由結果可以發現在相同流道高度下流率會隨熱通量提高而增加，與一般尺度下的趨勢一致。這是因為熱通量的提高會造成冷熱端溫差變大，造成磁體積力的差異變大進而造成流率的提高。在本實驗架設下，在熱通量459.8 kW/m^2、流道高度為350 µm時會有最高的流率為81.7 µL/min(Re=0.91)，這是因為管流的壓差理論與流體高Pr值特性的結果。由於本實驗屬於低Re值範圍，因此加熱區段前方流道溫度受到明顯的軸向熱傳現象溫度明顯上升。本研究利用量測結果計算了磁體積力與驅動壓力，在相同流道高度下驅動壓力會隨著熱通量的提高而增加，在本研究架設下可達到驅動壓力值約為6*〖10〗^4~12*〖10〗^4 N/m^2。

The study aims to examine the application of temperature-sensitive magnetic fluid in design of macro and micro scale magnetocaloric pump. The principle of the magnetocaloric pump is based on the decrease of magnetization of the temperature-sensitive magnetic fluid with the increase of temperature. In the experiments, the fluid started to move forward with applying a Gaussian distribution magnetic field and heating. In the test of macro scale magnetocaloric pumps, the result showed that the highest flow rate can be obtained when the positioning center of magnetic field aligning with the beginning of the heating area. Next, It was observed that the flow rate decreased with the tube length increasing from 1650 mm to 3150 mm under the magnetic field strength Hx,max=136 kA/m and heat flux q=5 kW/m^2 due to the friction between the tube and the fluid. Moreover, the experimental result showed that the flow rate increased and response time of the fluid decreased while the heat flux or magnetic field strength increased. In the micro-scale experiments, a self-pumping magnetocaloric pump was successfully constructed with a poly(methyl methacrylate)(PMMA) microchannel device which was made by the hot embossing process. The length and width of the microchannel were 10 and 1 mm, respectively. The flow rate and temperature at different locations along the microchannel were measured at four different microchannel height(180、290、350、420 µm) under different heat flux conditions. The result showed that the flow rate increased as the heat flux increasing, which was similar to the trend observed in the macro scale experiment. When the heat flux increased, the flow rate increased due to the increased temperature difference between the hot and cold area which created the gradient of magnetic body force. It was found that the highest flow rate of 81.7 µL/min(Re=0.91) can be obtained when the heat flux was 459.8 kW/m^2 and the microchannel height was 350 µm instead of 420 µm. This is due to the pressure drop inside the tube and the temperature-sensitive magnetic fluid property of high Prandtl number. The temperature data measured upstream of the heating area was observed with obvious temperature increasing due to the axial conduction which was common in the low Reynolds number flow in the micro-scale. The magnetic body force and driving pressure was also analyzed and it was found that the driving pressure increased as the heat flux increased under the same microchannel height. The driving pressure was around 6*〖10〗^4~12*〖10〗^4 N/m^2 estimated in this study.

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