Experimental analysis for the determination of the convective heat transfer coefficient by measuring pressure drop directly during annular condensation flow of R134a in a vertical smooth tube

DALKILIÇ A. S., Teke I., Wongwises S.

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, vol.54, no.4, pp.1008-1014, 2011 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 54 Issue: 4
  • Publication Date: 2011
  • Doi Number: 10.1016/j.ijheatmasstransfer.2010.06.057
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1008-1014
  • Keywords: Condensation, Two-phase pressure drop, Heat transfer coefficient, Vertical downward flow, R134a, VOID FRACTION MODELS, HIGH-MASS FLUX, 2-PHASE FRICTION FACTOR, DOWNWARD FLOW, PIPES
  • Yıldız Technical University Affiliated: Yes


This study investigated the direct relationship between the measured condensation pressure drop and convective heat transfer coefficient of R134a flowing downward inside a vertical smooth copper tube having an inner diameter of 8.1 mm and a length of 500 mm during annular flow. R134a and water were used as working fluids on the tube side and annular side of a double tube heat exchanger, respectively. Condensation experiments were performed at mass fluxes of 260, 300, 340, 400, 456 and 515 kg m(-2) s(-1) in the high mass flux region of R134a. The condensing temperatures were around 40 and 50 degrees C; the heat fluxes were between 10.16 and 66.61 kW m(-2). Paliwoda's analysis, which focused mainly on the determination of the two-phase flow factor and two-phase length of evaporators and condensers, was adapted to the in-tube condensation phenomena in the test section to determine the condensation heat transfer coefficient, heat flux, two-phase length and pressure drop experimentally by means of a large number of data points obtained under various experimental conditions. (C) 2010 Elsevier Ltd. All rights reserved.