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題名 | 環保冷媒(R407C)於絕熱毛細管中之模擬研究=The Simulation of Green Refrigerant (R-407C) in Adibatic Capillary Tubes |
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作者 | 馬小康; 郭明健; 陳逸傑; 陳群文; | 書刊名 | 國立臺灣大學工程學刊 |
卷期 | 87 2003.02[民92.02] |
頁次 | 頁81-88 |
專輯 | 「機械工程」專輯 |
分類號 | 446.641 |
關鍵詞 | R407C冷媒; 毛細管; 二相區; R407C refrigerant; Capillary; Two-phase region; |
語文 | 中文(Chinese) |
中文摘要 | 由於R-22冷媒具有溫室氣體效應將被禁止使用,然而R-407C冷媒具有與R-22相似的物理特性且不會造成溫室效應的溫升現象,所以被稱為環保冷媒並將被用來取代R-22。R-22冷媒在通過絕熱毛細管模式已被建立,並將膨脹過程區分為過冷液區、介穩態液區、介穩態二相區及平衡二相區 [1,2]。 本研究以數值分析方法探討R-407C使用於空調系統毛細管內時之流動特性,由於其為非共沸性冷媒,因此屆穩態區將不存在,流動過程只分為過冷液區及二相區,由於各成分沸點的不同,在二相區內存有溫度滑差的現象,因此需結合道爾吞分壓定律及羅德士定律以解出各成分汽化濃度及剩餘液體內之濃度。只要在背壓夠低的情況下毛細管出口會達到阻流狀態,此時之冷媒流量稱為阻流流量。由於阻流流量大小與膨脹過程相關且易於被量測,因此適合於以此作為模擬計算與實驗之精度比對指標。結果顯示其誤差值約在8% 左右。且如同R-22冷媒在加入毛細管入口形阻修正後,可提高數值模擬精度。 |
英文摘要 | Due to the global warming effect, R-22 refrigerant will be forbidden to use in the near future. R-407C refrigerant possess similar physical quality but does no harm to the surroundings, so it is called green refrigerant and it will replace R-22. A theoretical model was built for the flow of simple refrigerant (i.e., R-22) through adiabatic capillary tubes. It was characterized into a subcooled liquid region, a metastable liquid region, a metastable two-phase region, and an equilibrium two-phase region [1,2]. This study discusses flow characters of R-407C in the capillary tube of an air conditioner by using computer numerical simulation. Since R407C is not a co-boiling mixing refrigerant, metastable region can’t exist, the flow of refrigerant in capillary is regarded as two regions: the sub-cooled liquid region and two-phase region. Two-phase region undergoes temperature glide due to the different boiling point of the mixture ingredient. Individual concentration can be analyzed by the combination of Dalton’s law and Raoult’s law. The flow will be choked at the exit of the capillary tube if its backpressure is low enough. The mass flow of choked refrigerant, which is related to the process of phase change and easy to be measured, is an important index between the numerical simulation and the available experimental data. The simulation results show only about 8% difference comparing with the experimental data. The results also reveal that the capillary entrance effect is necessary to be taken into consideration to have a higher accuracy. |
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