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Journal of Enhanced Heat Transfer

Impact factor: 0.400

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v11.i4.40
pages 275-282

Condensation Heat Transfer and Pressure Drop of R22 in 5-mm Diameter Microfin Tubes

Xiaomin Wu
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, P. R. China
Xiaoliang Wang
Department of Thermal Engineering, Tsinghua University, Beijing 100084, China
Weicheng Wang
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, P. R. China

ABSTRACT

Condensation heat transfer coefficients and pressure drops of R22 in two microfin tubes with 5-mm outside diameter (OD) and a smooth tube with 5.4-mm OD were experimentally investigated. The main difference in geometries of the two microfin tubes was the helix angle: one had a helix angle of 7°, and the other had a helix angle of 18°. The test section had a length of 3.0 m and was divided into five subsections to achieve the local heat transfer coefficient. The condensation tests were carried out at 45 °C condensation temperature for 200−500 kg/m2s refrigerant mass fluxes with 5−30 °C inlet superheat degrees and 2−3 °C outlet subcooling degrees. The effects of helix angle and mass flux on the heat transfer coefficients and pressure drop are presented and discussed.