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Measured void fraction and heat transfer coefficients during condensation

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Abstract
Most work in literature on condensation in tubes has been done for smooth tubes in the horizontal and vertical configurations. Recent experimental works with condensation at different inclination angles showed that the heat transfer characteristics were a function of inclination angle. These works were limited to heat transfer and pressure drop measurements with visual observations. However, no work has been done on measuring the void fractions during condensation at different inclination angles. The purpose of this study was to measure void fractions and heat transfer coefficients during condensation for tube inclinations ranging from vertical downwards (-90) to vertical upwards (90) at a saturation temperature of 40C. Measurements were taken in an experimental set-up in which condensation occurred on the inside of a test section. The test section was a circular tube with an inner diameter of 8.38 mm and a heat transfer length of 1.488 m. The refrigerant used was R134a, and the void fractions were measured using two capacitive void fraction sensors. A mass flux of 100 kg/m2.s and vapour qualities ranging from 10 – 90% were considered. Heat transfer coefficients were also compared with void fractions. It was found that at low mass fluxes and vapour qualities, void fraction and heat transfer were significantly affected by changes in inclination angle. Generally, void fractions and heat transfer coefficients increased with downward inclination angles with an optimum angle between -10 and -30 (downward flow). At some vapour quality conditions, the void fraction and heat transfer coefficients were observed to be independent of the inclination angle despite changes in the prevailing flow patterns.
Keywords
void fraction, heat transfer coefficient, Condensation, refrigerant

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MLA
Olivier, Stefan, Josua Meyer, Michel De Paepe, et al. “Measured Void Fraction and Heat Transfer Coefficients During Condensation.” 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings. Ed. Josua Meyer. 2015. 408–416. Print.
APA
Olivier, S., Meyer, J., De Paepe, M., & De Kerpel, K. (2015). Measured void fraction and heat transfer coefficients during condensation. In Josua Meyer (Ed.), 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings (pp. 408–416). Presented at the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT).
Chicago author-date
Olivier, Stefan, Josua Meyer, Michel De Paepe, and Kathleen De Kerpel. 2015. “Measured Void Fraction and Heat Transfer Coefficients During Condensation.” In 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings, ed. Josua Meyer, 408–416.
Chicago author-date (all authors)
Olivier, Stefan, Josua Meyer, Michel De Paepe, and Kathleen De Kerpel. 2015. “Measured Void Fraction and Heat Transfer Coefficients During Condensation.” In 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings, ed. Josua Meyer, 408–416.
Vancouver
1.
Olivier S, Meyer J, De Paepe M, De Kerpel K. Measured void fraction and heat transfer coefficients during condensation. In: Meyer J, editor. 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings. 2015. p. 408–16.
IEEE
[1]
S. Olivier, J. Meyer, M. De Paepe, and K. De Kerpel, “Measured void fraction and heat transfer coefficients during condensation,” in 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings, Kruger National Park, South Africa, 2015, pp. 408–416.
@inproceedings{6885337,
  abstract     = {Most work in literature on condensation in tubes has been
done for smooth tubes in the horizontal and vertical
configurations. Recent experimental works with condensation
at different inclination angles showed that the heat transfer
characteristics were a function of inclination angle. These
works were limited to heat transfer and pressure drop
measurements with visual observations. However, no work has
been done on measuring the void fractions during condensation
at different inclination angles. The purpose of this study was to
measure void fractions and heat transfer coefficients during
condensation for tube inclinations ranging from vertical
downwards (-90) to vertical upwards (90) at a saturation
temperature of 40C. Measurements were taken in an
experimental set-up in which condensation occurred on the
inside of a test section. The test section was a circular tube with
an inner diameter of 8.38 mm and a heat transfer length of
1.488 m. The refrigerant used was R134a, and the void
fractions were measured using two capacitive void fraction
sensors. A mass flux of 100 kg/m2.s and vapour qualities
ranging from 10 – 90% were considered. Heat transfer
coefficients were also compared with void fractions. It was
found that at low mass fluxes and vapour qualities, void
fraction and heat transfer were significantly affected by
changes in inclination angle. Generally, void fractions and heat
transfer coefficients increased with downward inclination
angles with an optimum angle between -10 and -30
(downward flow). At some vapour quality conditions, the void
fraction and heat transfer coefficients were observed to be
independent of the inclination angle despite changes in the
prevailing flow patterns.},
  author       = {Olivier, Stefan and Meyer, Josua and De Paepe, Michel and De Kerpel, Kathleen},
  booktitle    = {11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings},
  editor       = {Meyer, Josua},
  isbn         = {9781775921080},
  keywords     = {void fraction,heat transfer coefficient,Condensation,refrigerant},
  language     = {eng},
  location     = {Kruger National Park, South Africa},
  pages        = {408--416},
  title        = {Measured void fraction and heat transfer coefficients during condensation},
  year         = {2015},
}