本論文主要為研究銀奈米流體於溝槽式熱管與燒結式熱管之性能影響。實驗中之銀奈米顆粒之粒徑為10奈米與35奈米。在實驗過程以量測奈米流體與純水充填於熱管之溫差，進而計算其熱阻來比較其性能差異。溝槽式熱管於30~60W輸入功率下，當工作流體為銀奈米流體時其熱阻較純水充填熱管之降低範圍在10%~80%。另外，實驗結果顯示溝槽式熱管之熱阻，隨著銀奈米流體濃度與銀奈米顆粒之上升，而有較低之熱阻。在燒結式熱管於輸入功率為30~50W時，銀奈米流體熱管之溫差，相較於純水熱管小了0.56℃~0.65℃。此外，銀奈米流體充填於燒結式熱管中，可達70W之操作功率，相較於工作流體為純水時高了20W之操作功率 第二部份為研究銀奈米流體之濃度與粒徑，於銅板試片表面沾溼性之影響。實驗結果顯示，表面沾溼性隨著銀奈米流體濃度與粒徑而改變。另外，研究中主要發現奈米顆粒成份比重，奈米多孔結構之分佈及奈米流體濃度為主要影響接觸角變化之主要因素。 第三部份將初步探討奈米流體於熱管之提升熱傳機制(有效熱傳導係數，表面沾溼性及對流熱傳)。由於表面沾溼性的改變，導致毛細作用力,臨界熱通量及冷凝效果之提升。因此，奈米流體改變表面沾溼性為熱管性能提昇之主要機制。 The purpose of this thesis is to study the effects of silver nano-fluids on grooved heat pipe and sintered heat pipe thermal performance. The nano-fluid used in this study is an aqueous solution of 10 nm and 35nm diameter silver nanoparticles. The experiment was performed to measure the temperature distribution and compare the heat pipe thermal resistance using nano-fluid and DI-water. The experimental result of grooved heat pipe showed that thermal resistance decreased 10%~80% compared to DI-water at an input power of 30~60W. And the measured results also show that the thermal resistances of the heat pipe decrease as the silver nanoparticle size and concentration increase. The experimental result of sintered heat pipe, the nano-fluids filled heat pipe temperature distribution demonstrated that the temperature difference decreased 0.56~0.65℃ compared to DI-water at an input power of 30~50W. And the nano-fluid as working medium in heat pipe can up to 70W and is higher than pure water about 20W.
In addition, the characteristics of silver nano-fluid concentrations and sizes on copper plate surface wettability were investigated. The experimental results presented that the surface wettability changed with the nano-fluid concentrations and particle sizes. The most significant finding was that the nanoparticle composition percentage, nano-porous layer distribution and particle concentration were influenced mainly by the contact angle.
The fundamental mechanisms (effective thermal conductivity, surface wettability and convective heat transfer) of enhanced heat transfer for heat pipes have taken the first step to investigate. The results showed that surface wettability enhancement can be mainly mechanism in improved the heat pipe thermal performance. Due to a significant increase in wettability, thus leading to the capillary force, critical heat flux and condensation enhancement.