以鎳鈦合金作為固態冷媒之空調原型機研製

Abstract

本研究探討採用鎳鈦合金作為潔淨能源材料之固態冷媒，以彈熱效應的原理開發彈 熱材料應用於空調系統的原型機研製。透過鎳鈦合金本身擁有形狀記憶效應及超彈性的 的性質，受應力誘發產生麻田散體相變態，造成彈熱材料發生放熱效應，相反的，當應 力釋放後產生逆相變態造成彈熱材料發生吸熱效應，此時透過低溫的彈熱材料與空調系 統內的空氣熱交換，將低溫氣體排出系統外達到環境降溫的效果。 為了開發彈熱空調系統原型機，分析鎳鈦合金受應力造成的溫度變化關係，建立彈 熱材料溫度變化與端凸輪角度關係式，設計驅動彈熱材料應變之端凸輪機構。實驗採用 直徑 0.5 mm 之鎳鈦合金線，設計合金線的挾持機構，使合金線能夠延端凸輪位移方向 拉伸及回彈產生熱效應，並隨端凸輪軸向方向移動旋轉，使彈熱材料在不同的流道位置 產生連續熱效應。設計空氣熱交換流道系統與風切機構改良過去文獻模擬發生冷熱氣體 混風問題。 量測彈熱空調原型機中彈熱材料溫度變化，以及冷端流道出口位置的溫度變化，計 算此空調系統原型機的 COP。根據實驗結果顯示，由於流道機構內之彈熱材料質量較 小，導致不足以劇烈的影響流道系統中空氣熱傳，因此 COP 的增幅並不如預期明顯。 將實驗數據與理論分析計算後的溫度變化及 COP 進行比較，由於流道機構的熱傳、鎳 鈦合金線的挾持問題等等，使量測實驗之 COP 較小。這項研究的目的在於透過潔淨能 源材料鎳鈦合金有效產生冷卻效果應用於製冷效應循環之空調系統，實現具有潛力取代 傳統空調系統冷媒之彈熱材料應用。

This study explores the use of nickel-titanium (NiTi) alloy as a solid-state refrigerant material for clean energy applications, specifically developing a prototype air conditioning system based on the elastocaloric effect. Utilizing the shape memory effect and superelasticity inherent in NiTi alloys, stress-induced martensitic phase transformation occurs, leading to an exothermic effect in the elastocaloric material. Conversely, when the stress is released, a reverse phase transformation causes an endothermic effect, allowing the low-temperature elastocaloric material to exchange heat with the air in the air conditioning system, expelling the cooled air outside to achieve an environmental cooling effect. To develop the prototype elastocaloric air conditioning system, the temperature change relationship caused by stress in the NiTi alloy is analyzed, establishing a correlation between temperature change and cam angle. A cam mechanism is designed to drive the strain of the elastocaloric material. Experiments utilize NiTi alloy wires with a diameter of 0.5 mm. A clamping mechanism for the alloy wire is designed to stretch and recoil the wire along the cam displacement direction, generating a thermal effect, and to rotate axially along the cam shaft direction, causing continuous thermal effects at different flow channel positions. An air heat exchange flow channel system and fan mechanism are designed to improve the cold-hot air mixing issue observed in previous studies. The temperature changes of the elastocaloric material and the outlet temperature of the cold end flow channel are measured, and the COP of the prototype air conditioning system is calculated. Experimental results indicate that due to the small mass of the elastocaloric material within the flow channel mechanism, the heat transfer effect on the airflow system is insufficient to significantly impact the COP as expected. By comparing the experimental data with theoretical calculations of temperature changes and COP, it is found that issues such as heat transfer within the flow channel mechanism and clamping problems of the NiTi alloy wire result in a lower measured COP. The aim of this study is to effectively produce a cooling effect using clean energy material NiTi alloy for application in cooling cycle air conditioning systems, demonstrating the potential of elastocaloric materials to replace traditional refrigerants in air conditioning systems.