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  • 學位論文

數值模擬分析可變基圓半徑圓漸開線渦卷式壓縮機的熱流特性

Numerical Study on the Thermal-Fluid Fields inside the Scroll Compressor with Involute of Variable-Radii Circle

指導教授 : 黃博全
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摘要


渦卷式壓縮機因具有效率佳、噪音小及可靠性高的優點,深受冷凍空調市場的歡迎,但受限於排氣量,僅能用在中低噸位的空調機上。本文利用可變基圓半徑圓漸開線取代固定基圓半徑圓漸開線,設計出在相同渦盤尺寸大小、高度及圈數下,具有較大排氣量的機型,以達到增加壓縮機適用範圍與節能減碳之目標。研究方法是以現有商用機型為基礎,設計一具可變基圓半徑圓漸開線之渦卷式冷媒壓縮機,並以數值方法,探討在不同設計參數下,壓縮室內熱流場之特性與其對壓縮機運轉之影響。 模擬結果發現:(1)相較於固定基圓半徑圓漸開線,可變基圓半徑圓漸開線渦卷之壓縮室內部壓力隨轉動角度的變化較小; (2)在同一高度及渦卷圈數下,可變基圓半徑圓漸開線渦卷之排氣量,會隨著可變半徑增量δ_0值增加而增大,反之則排氣量減小;(3)在δ0= -0.035時,可變基圓半徑圓漸開線渦卷的排氣量較固定基圓半徑圓漸開線渦卷增大了31.24%,入出口焓值減少了8.8%,容積效率和壓縮效率皆提高;(4)由於鄰近壓縮室壓差關係,可變基圓半徑圓漸開線渦卷較固定基圓半徑圓漸開線渦卷洩漏減少; (5)渦卷體修正齒頭(the center of the scroll pair)造形的β角越大,第三壓縮室的上腔室排氣時程提前越多。

並列摘要


The scroll compressor is popular in the industry of refrigeration and air-conditioning , because it is high efficiency, low noise and high reliability. Due to the limitation of the scroll compressor displacement, the scroll compressor is used in the small situation of the refrigeration and air-conditioning,. In order to match wider loading conditions, save energy and reduce carbon, this study replaces an involute of constant-radii circle with an involute of variable-radii circle to design the scroll compressor with larger displacement without changing the diameter of a base plate, wrap height and the number of turns. The research method is based on the commercial scroll compressor to design a scroll compressor with an involute of variable-radii circle. A numerical investigation is applied to explore the characteristic of the thermal-fluid fields inside in compression chamber with the difference design parameters. The simulation results show that: (1) The rate of change of rotation angle internal pressure inside for the involute profile of variable-radii circle is smaller than that for the involute profile of constant-radii circle (2) Under the wrap height and the number of turns as the increment δ0 increases, the displacement of scroll compressor with involute of variable-radii circle becomes larger. Conversely displacement reduce; (3) Compared to the scroll compressor with involute of constant-radii circle, when δ0=-0.035, the displacement increases 31.24% ,the enthalpy difference between inlet and outlet decreases 8.8%, the volumetric efficiency and compressor efficiency increases, for the case with involute of variable-radii circle; (4) The amount of leakage, caused by the pressure difference between two adjacent compression chamber, have a significantly reduce, for the case with variable-radii circle than for that with fixed-radii circle; (5) It is found that a greater modified angle β between the outer and inner involute curve results in a earlier exhaust process the time of the exhaust is advanced for the upper chamber of the third compression.

參考文獻


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