標題: Experimental study of evaporation pressure drop characteristics of refrigerants R-134a and R-407C in horizontal small tubes
作者: Lie, Y. M.
Su, F. Q.
Lai, R. L.
Lin, T. F.
機械工程學系
Department of Mechanical Engineering
公開日期: 1-Jan-2008
摘要: An experiment is carried out in the present study to investigate the characteristics of the frictional pressure drops for the evaporation of refrigerants R-134a and R-407C in horizontal small tubes having the same inside diameter of 0.83 mm or 2.0 mm. In the experiment for the 2.0-mm tubes, the refrigerant mass flux G is varied from 200 to 400 kg/m(2) s, imposed heat flux q from 5 to 15 kW/m(2), inlet vapor quality x(in) from 0.2 to 0.8, and refrigerant saturation temperature T-sat from 5 to 15 degrees C. While for the 0.83-mm tubes, G is varied from 800 to 1500 kg/m(2) s with the other parameters varied in the same ranges as those for D-i = 2.0 mm. In this study, the effects of the inlet refrigerant vapor quality, mass flux, saturation temperature and imposed heat flux on the measured frictional pressure drops are examined in detail. Our experimental data clearly show that both the R-134a and R-407C frictional pressure drops increase significantly with the inlet vapor quality of the refrigerant, except at low mass flux and high heat flux. Besides, the effect of the imposed heat flux on the frictional pressure drop is rather weak. Moreover, a significant decrease in the frictional pressure drop results for a rise in T-sat. Furthermore, both the R-134a and R-407C frictional pressure drops increase substantially with the refrigerant mass flux. We also note that under the same x(in), T-sat, q and D-i, refrigerant R-407C has a lower frictional pressure drop when compared with that for R-134a. For the same refrigerant, a reduction in the duct size from 2.0-mm to 0.83-mm causes a significant increase in Delta P-f. Finally, an empirical correlation for the friction factor for the R-134a and R-407C evaporation in the 0.83-mm and 2.0-mm small tubes is proposed. (C) 2007 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2007.03.046
http://hdl.handle.net/11536/9815
ISSN: 0017-9310
DOI: 10.1016/j.ijheatmasstransfer.2007.03.046
期刊: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Volume: 51
Issue: 1-2
起始頁: 294
結束頁: 301
Appears in Collections:Articles


Files in This Item:

  1. 000252688800028.pdf