Evaporative heat transfer in vertical circular microchannels
2004 (English)In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 24, no 8-9, 1241-1253 p.Article in journal (Refereed) Published
This paper presents new experimental results on saturated flow boiling in microchannels. Heat transfer coefficients were measured for saturated boiling of R134a in vertical circular tubes with internal diameters of 1.7, 1.224 and 0.826 mm, and a uniformly heated length of 220 mm. Heat transfer coefficients were obtained for a heat flux range of 3-34 kW/m(2), a mass flux range of 50-400 kg/m(2) s, and vapour qualities up to 0.6. Experiments were conducted at two different pressures, 8.626 and 6.458 bars. Heat transfer coefficients were found to be a strong function of the wall heat flux and system pressure, while being fairly independent upon mass flux and vapour quality. This suggests that the heat transfer mechanism is strongly related to that in nucleate boiling.
Place, publisher, year, edition, pages
2004. Vol. 24, no 8-9, 1241-1253 p.
Flow boiling; Heat transfer; Microchannel; Enthalpy; Evaporation; Evaporators; Heat flux; Heat pump systems; Heat transfer coefficients; Nucleate boiling; Specific heat; Thermal conductivity; Thermodynamics; Viscosity; Flow boiling; Microchannels; Heat transfer
IdentifiersURN: urn:nbn:se:kth:diva-6865DOI: 10.1016/j.applthermaleng.2003.12.030ISI: 000221204600011ScopusID: 2-s2.0-1842576519OAI: oai:DiVA.org:kth-6865DiVA: diva2:11695
QC 201008122007-03-092007-03-092011-10-26Bibliographically approved