TED-AJ03-200 EXPERIMENTAL STUDY ON VAPOR-LIQUID TWO-PHASE FLOW OF R134A INSIDE SMOOTH AND MICROFIN TUBES: RELATION OF VOID FRACTION AND VAPOR QUALITY AT ADIABATIC CONDITION :

Shigeru Koyama, Joodong Lee, Yongchang Chen, Ryuuichirou Yonemoto

    Research output: Contribution to journalArticle

    Abstract

    Void fraction is one of the important parameters in heat transfer and fluid flow characteristics for vapor-liquid two-phase flow. It is worthwhile to predict the void fraction in a microfin tube as a function of the design and operating parameters of the heat exchanger since most of the air-conditioning systems adopt microfin tubes widely to improve their efficiency. However, there are only a few studies found in the literature and the characteristics of void fraction in a microfin tube are not clarified yet because of insufficient data. The present paper deals with experiments for the void fraction of R134a vapor-liquid two-phase flow in horizontal smooth and microfin tubes under adiabatic condition. The void fraction was measured by the quick closing valve method. The smooth tube tested is 1000[figure]mm in length and 7.52 mm in inside diameter. The microfin tube tested is 8.86 mm in mean inside diameter and 1000 mm in length; the fin height is 0.18 mm, the helix angle of fins is 25 degrees and the fin numbers are 70. The experimental data were obtained in the ranges of vapor quality from 0.01 to 0.96 at pressure ranges between 1.2 and 0.8 MPa, and at mass flow rate of 20 and 40 kg/h. The experimental results show that the void fraction for smooth tube is well correlated by the Smith and the Baroczy correlations within ±10%. It is also confirmed that the void fraction in the microfin tube is lower than that of smooth tube in any quality and the prediction results using previous correlations for smooth tube are higher than the present experimental data of microfin tube.[figure]
    Original languageEnglish
    Pages (from-to)319
    JournalProceedings of the ... ASME/JSME Thermal Engineering Joint Conference
    Volume2003
    Issue number6
    Publication statusPublished - 2003

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