氧化鋁奈米流體應用於綠能動力系統散熱性能之研究

Abstract

熱管理系統攸關於綠能動力的輸出效率，其中散熱所使用的工作流體的熱性能將直接影響熱管理系統的性能。本研究使用Al2O3/Water奈米流體作為綠能動力散熱系統之工作流體，並實際與水相比較來評估其差異與可行性。首先，本研究使用二階合成法製備出Al2O3/Water奈米流體，並針對不同的溫度與濃度之下的熱傳導係數、流體密度、黏滯係數及比熱等基礎性質進行量測與分析。再者將Al2O3/Water奈米流體實際應用散熱系統之中，針對不同流速、溫度、濃度及加熱功率進行散熱性能與水泵耗電量的測試與評估。研究結果顯示，Al2O3/Water奈米流體在濃度1.5wt.%、2.1 L/min.及30℃的測試條件之下，熱交換量比水高39%；然而在1.5wt.%、流量2.1 L/min.及60℃的測試條件之下，水泵則呈現最高的耗電量。為了尋求最佳的系統配置參數，本研究同時考量散熱能力與水泵消耗功率而提出效率因子比(REF)來評估散熱系統的整體效能。經過分析評估發現，在低濃度與低流率的條件之下，Al2O3/Water奈米流體有較佳的整體效能，其效率因子比最高可達1.31。相關研究結果顯示使用Al2O3/Water奈米流體在綠能動力的熱管理系統之中具有縮減散熱器與水泵體積的潛力，對於電動車輛的配置空間、載重與續航力將能有所貢獻。

A thermal management system is strongly related to the output efficiency. The employed working fluid will directly influence the performance of the entire thermal management system. This research adopts Al2O3/Water nanofluid as the working fluid. The difference and feasibility compared with water was conducted. First, this research used a two step synthesis method to produce Al2O3/water nanofluid. The thermal conductivity coefficient, fluid density, viscosity coefficient and specific heat under different temperatures and concentrations were measured and analyzed. Moreover, the Al2O3/Water nanofluid was employed in a heat dissipation system to test and evaluate the heat dissipation performance and pumping power under different flow rates, temperatures, concentrations and heating power. The research results show that the heat exchange capacity is 39% higher than water under concentration of 1.5wt%, flow rate of 2.1 L/min. and temperature at 30℃. Moreover, the pumping power is highest at concentration of 1.5wt.%, flow rate of 2.1 L/min. and temperature at 60℃. To search for the optimal parameters, this research consider proposed an efficiency factor ratio to accommodate the heat dissipation capacity and the pumping power. After data analysis, at low concentration and low coolant flow rate, the efficiency factor ratio for the system is better. The highest ratio is to 1.31. The related research results indicate that the Al2O3/Water nanofluid utilized in the thermal management system of green energy sources has the potential to scale down the occupied space of the heat exchanger and the coolant pump. That is expected to bring a lot of benefit for the equipped space in and cruising mileage of an electric vehicle in the near future.