熱動式壓縮機的工作原理類似於史特靈引擎但與理想的史特靈循環在性能上仍有些許的差別,熱壓縮機主要以熱能提高系統內氣體的壓力並配置適當的進氣閥門及排氣閥門以達成低壓氣體導入高壓流體排出的效果。 本文主旨在於以節點分析法採用文獻[1]的模式建立一套熱壓縮機系統的模型,將能量方程式中造成溫度變化的各項因素分開處理已達到穩定的數值分析。在系統加熱區及散熱區考慮氣體與金屬壁面熱傳的發生有別於以往以等溫及絕熱兩種極端的假設,此模擬結果能直接的表示出系統內的循環現象。 經由模擬分析而得的結果顯示出系統各元件尺寸的設計對於系統循環的運轉性能具有相當大的影響力。此外系統選用的工作流體與系統曲柄的轉速必須互相配合,良好的組合可使系統達到極佳的運轉性能,而過分的提高曲柄的運轉速度可能導致整個系統完全喪失效果。
Thermal compressor is a member of the Stirling family of thermodynamic devices, but differs from such devices inasmuch as it uses thermal energy to compress gas rather than to produce shaft work. Compression is achieved by fitting inlet and exhaust valves to the working spaces, and permitting gas with the same type as working fluid to be induced at a low pressure and exhausted at a higher pressure in a quasi-continuous manner. The scope of this research uses Nodal Analysis Method to establish the mathematical model of thermal compressor. This model decouples three processes that contribute to the temperature change in the energy equation and solves for the temperature change in each process respectively in order to avoid numerical instability problems. This model differs from the two extreme assumptions, isothermal and adiabatic processes that were used to assuming in the working spaces, in calculating the temperature change in the working spaces and considering the heat transfer between gas and metal of the system. Using this model to analyze the thermal compressor system can get the result of cycle phenomenon directly. The result of analyzing this simulation shows that each component size designed of the system influence its performance significantly. In addition, this result also tells us that choosing working fluid compressed and using rotational speed of crank must cooperate with each other well. A good cooperation will accomplish the perfect performance of the system. On the other hand, rising excessively rotational speed of crank will make the system failed.