以彈熱材料作為固態冷媒之空調機熱傳理論分析與數值模擬研究

Abstract

本研究探討以彈熱材料作為固態冷媒的空調機系統，聚焦於其熱傳理論分析與數值模擬。研究首先從 Clausius-Clapeyron 方程式出發，推導出彈熱材料的理論絕熱溫度變化方程式。依據凸輪配置和應變率，建立了負載段、熱端維持段、卸載段和冷端維持段的溫度變化方程式，為彈熱空調系統提供理論基礎。 在數值模擬方面，本研究採用計算流體動力學(CFD)方法，使用 FLUENT 軟體進行彈熱空調的模擬。為解決冷熱端混風問題，創新性地提出了風牆設計，並引入x_1、x_2、x_3與x_4等參數來量化分析混風情況。研究探討了不同入口流速（1 m/s、3 m/s、5 m/s）、風牆壓力和材料組數（24組、48組、96組）對空調性能的影響。 研究結果表明，低入口流速（1 m/s）和較多的材料組數（96組）能夠顯著提升空調的溫度變化效果，在此最佳條件下，冷端入出口溫差達到 1.57 K，熱端入出口溫差達到 1.63 K。並且結果顯示增加材料組數不僅提高了溫度變化效果，還增加了出口溫度的穩定性。 本研究通過理論分析和數值模擬，為彈熱材料在空調系統中的應用提供了重要參考。研究結果不僅展示了彈熱空調系統的潛力，也為未來系統優化提供了方向。風牆設計的創新應用解決了關鍵的混風問題，為實際應用奠定了基礎。未來研究可以進一步探索材料選擇、系統結構優化以及多台串聯等方向，以進一步提升彈熱空調的性能和實用性。

This study investigates an air conditioning system using elastocaloric materials as solid-state refrigerants, focusing on heat transfer theoretical analysis and numerical simulation. The research begins by deriving the theoretical adiabatic temperature change equation for elastocaloric materials from the Clausius-Clapeyron equation. Based on cam configuration and strain rate, temperature change equations for the loading, hot-end holding, unloading, and cold-end holding stages were established, providing a theoretical foundation for the elastocaloric air conditioning system. For numerical simulation, this study employs Computational Fluid Dynamics (CFD) methods using FLUENT software to simulate the elastocaloric air conditioner. To address the mixing flow problem between hot and cold ends, an innovative air-cutter design was proposed, introducing parameters x_1, x_2, x_3 and x_4 to quantitatively analyze flow mixing. The study examined the effects of different inlet velocities (1 m/s, 3 m/s, 5 m/s), air-cutter pressures, and material group numbers (24, 48, 96 groups) on air conditioning performance. The research findings indicate that the lower inlet velocity and higher number of used material significantly enhance the temperature change effect of the air conditioner. Under optimal conditions, the cold-end inlet-outlet temperature difference reaches 1.57 K, and the hot-end inlet-outlet temperature difference reaches 1.63 K. The results also show that increasing the number of material does not only increase the temperature change of the air conditioner, but also the stability of the outlet temperature. This study provides important references for the application of elastocaloric materials in air conditioning systems through theoretical analysis and numerical simulation. The results demonstrate the potential of elastocaloric air conditioning systems and provide directions for future system optimization. The innovative application of the air-cutter design addresses the critical mixing flow problem, laying a foundation for practical applications. Future research can further explore material selection, system structure optimization, and multi-unit series connection to further enhance the performance and practicality of elastocaloric air conditioning.