磁流體粒子濃度於振動能量收集器發電效率之研究

Study on particle concentration effect of magnetic fluids on the electrical efficiency of a vibrational energy harvester

陳立宇(Li-Yu Chen)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程研究所/碩士(2019年)

https://doi.org/10.6840/cycu201900722

摘要

本論文進行磁流體粒子濃度於振動能量收集器發電效率之分析。主要目的在探討振動能量收集器之幾何外型、添加之磁流體粒子濃度，以及磁流體體積占比對發電效率的影響。首先，我們完成奈米等級的水基磁流體的製備。接著，設計振動平台以模擬振動能量收集器於不同頻率下的振動情況。最後，我們收集各項實驗數據，進而探討幾何、濃度，以及體積占比對發電效率的影響。
由實驗結果發現，振動能量收集器中裝載磁鐵的槽體其幾何外型對於發電效率有相當顯著的影響，當在槽體中添加粒子濃度為2%的磁流體時，槽體長度應越接近磁鐵長度，而槽體直徑應與磁鐵直徑越接近越好。當磁流體粒子濃度為3%時，磁流體能夠支撐磁鐵，讓磁鐵懸浮於槽體內，使發電效率大幅提升。在相同頻率下不同振幅的實驗結果顯示，隨振幅的增加，發電效率也隨之增加，但當振幅超過槽體長度，發電效率則轉而下降。磁流體的體積占比亦會影響發電效率，當體積占比為80%時，槽體中少量的空氣使磁鐵有更好的運動性，進而讓發電效率提升；當磁流體體積占比小於60%時，過多的空氣會與磁流體產生綿密氣泡，造成發電效率下降。

關鍵字

磁性奈米流體 ； 能量收集 ； 振動發電機 ； 體積分率

並列摘要

This study is conducted with particle concentration effect of magnetic fluids on the power efficiency of a vibrational energy harvester. The main purpose is to investigate the effects of vibrational energy harvester geometry, added magnetic-fluid particle concentration, and magnetic-fluid volume fraction on the power efficiency. First, we complete the chemical preparation of nano-scale water-based magnetic fluids, and determine its volume fraction. Next, we design a vibration platform with vibration of different frequencies. Finally, we collect the experimental data to investigate the power efficiency.
Experimental results reveal that the geometry of a vibration energy harvester plays an important role in power efficiency. When the volume fraction of the added magnetic-fluid is 2%, the length of tank should be close to the magnet, and the diameter should be as close as possible to the diameter of the magnet. When the volume fraction of the magnetic fluid is up to 3%, the magnetic fluid is able to support the magnet and suspend the magnet in the tank, so that the power efficiency has a significant increase. For the experimental results with different amplitudes at the same frequency, we found that the power efficiency increases with the increase of the amplitude. But when the amplitude is greater than the length of the tank, the power efficiency gets lower instead. At experiment for the effect of magnetic-fluid volume fraction, we found that when the magnetic-fluid volume fraction is 80%, a small amount of air in the tank can help the magnet move more smoothly and enhance the power efficiency. When the magnetic-fluid volume fraction is less than 60%, excessive air can create dense foam with the magnetic fluid, and interfere with the mobility of magnet, causing a decrease in power efficiency

並列關鍵字

magnetic nanofluids ； energy harvesting ； vibration generator ； volume fraction

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