ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
CONDENSATION HEAT TRANSFER OF R-134A ON SINGLE HORIZONTAL THREE-DIMENSIONAL STRUCTURED TUBES
摘要
Condensation heat transfer coefficients were experimentally investigated on four structured tubes having three-dimensional fin geometries on the outside and helical ribs on the inside of the tubes. Tests were conducted using R-134a at a saturation temperature of 35°C. The outside diameter of the tubes is 19 mm and the length of the test section is 1002 mm. Heat flux and cooling water flow rate are varied in a wide range. Shell-side heat transfer coefficients are obtained from overall heat transfer data and the implementation of commonly used correlations for tube- and shell-side heat transfer. Experimental results for a plain tube are in good agreement with Nußelt film theory. During the tests of the structured tubes, considerable enhancement for shell-side and tube-side heat transfer coefficients are observed as compared to the plain tube. Enhancement factors for condensation heat transfer are ranged from 14.8 to 27.4 at a heat flux of 20 kW/m². Due to differences in outer fin geometries, significant impact of small scale parameters on condensation performance was identified.