隨著全球電動車快充基礎設施邁向高功率化發展，單體功率達80 kW之交直流電源轉換模組發熱密度急遽攀升。在約3%之能量轉換損耗下，液冷板底面必須於150 mm×250 mm的接觸面積內移除高達2400 W之廢熱，對應熱通量高達64,000 W/m^2。傳統採用純水作為工作流體之單相液冷系統，流體沿迂迴之S型流道行進時快速升溫，導致下游散熱能力衰退，並在加熱面上引發嚴重的局部熱堆積與劇烈溫差；若以提高流量的方式提升散熱效果，會造成流道壓力損失劇增與泵浦高耗能之實務困境。為突破單相水冷之物理極限，本研究導入兼具流動性與固-液相變潛熱吸熱特性之相變化乳液(Phase Change Material Emulsion, PCME)作為工作流體。本研究建構三維 S 型迂迴流道液冷板共軛熱流數值模型，選用純水作為對照組，並搭配三種不同正二十烷微膠囊質量濃度(5%、10%、20%)之相變化乳液，針對0.50至2.0 L/min等進口體積流量進行系統化模擬與物理機制解析。
模擬結果顯示，相變化乳液能吸收大量潛熱，有效抑制流體沿流向之溫升並延緩下游熱堆積。若以「最大容許溫度(368 K)」為基礎安全規範，純水於極低流量(0.5 L/min)時最高壁溫突破384 K(εT,max < 0)，面臨熱過載風險；而各濃度相變化乳於同流量下皆能將最高溫控制於安全規範368 K以內(εT,max > 0.15)。若進一步以更高標準的「最佳運行溫度(338 K)」檢視，純水在所有測試流量下皆全面失效(εT,opt < 0)；反觀相變化乳液，當流量提升至1.2 L/min以上，即可成功將壁面最高溫壓制在最佳運行溫度以內(εT,opt > 0)，相較於純水，相變化乳液展現出顯著的散熱優勢。
值得注意的是，濃度最高之20%乳液雖具備最大潛熱容量與最優異之表面均溫性，但固態微膠囊低導熱性質稀釋了連續相傳熱效率，使其平均熱傳導係數衰退至約0.49 W/m∙K，由於流體近壁邊界層內的傳熱機制高度仰賴熱傳導，20%乳液的高黏度不僅導致邊界層顯著增厚，再加上其較差的熱傳導能力，雙重劣勢大幅放大了固-液交界面之熱阻，使其最高溫抑制表現反而不如5%與10%濃度。此外，經由綜合效能指標(FOM)全面權衡對流熱傳增益(εh)與進出口壓降(ΔP)，證實0200%乳液因高黏度使進出口壓降劇增，導致綜合表現最差。最終，綜合考量溫控安全性、溫度分布均勻度與泵浦節能，本研究確立採用10%質量濃度之相變化乳液搭配大於1.5 L/min之進口流量，為該80 kW高功率電源轉換模組散熱系統之最優配置。

This study investigates the thermal management of an 80 kW power conversion module in extreme fast charging (XFC) stations. Operating at a severe heat flux of 64,000 W/m^2, traditional water-cooling systems suffer from downstream thermal accumulation along the S-shaped liquid cold plate. To overcome this limitation, a three-dimensional conjugate heat transfer model was developed to evaluate the cooling performance of Phase Change Material Emulsions (PCME) containing n-eicosane microcapsules at mass concentrations of 5%, 10%, and 20%, under flow rates ranging from 0.5 to 2.0 L/min. Results indicate that PCME effectively absorbs latent heat, drastically suppressing the maximum wall temperature and enhancing spatial temperature uniformity. While the 20% PCME exhibited the best temperature uniformity, its maximum temperature suppression was inferior to the 10% PCME. This inversion is attributed to the emulsion's lower thermal conductivity and significantly higher viscosity, which thickens the near-wall thermal boundary layer and increases conduction resistance. By comprehensively evaluating the thermal resistance, convective heat transfer coefficient, and pumping power penalty (Figure of Merit), the 10% PCME at flow rates above 1.5 L/min is identified as the optimal configuration, successfully maintaining the module below the stringent optimum operating temperature of 338 K.

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