Convective condensation inside horizontal smooth and microfin tubes

Summary, in English

An experimental investigation was performed for convective condensation of R410A

inside one smooth tube (3.78 mm, inner diameter) and six microfin tubes (4.54, 4.6 and

8.98 mm, fin root diameter) of different geometries for mass fluxes ranging from 99 to 603

kg m-2s-1. The experimental data were analyzed with updated flow pattern maps and

evaluated with existing correlations. The heat transfer coefficient in the microfin tubes

decreases at first and then increases or flattens out gradually as mass flux decreases.

This obvious non-monotonic heat transfer coefficient-mass flux relation may be explained

by the complex interactions between the microfins and the fluid, mainly by surface

tension effects. The heat transfer enhancement mechanism in microfin tubes is mainly

due to the surface area increase at large mass fluxes, while liquid drainage by surface

tension and interfacial turbulence enhance heat transfer greatly at low mass fluxes.

• Author: Zan Wu; Bengt Sundén; Lei Wang; Wei Li
• Department/s: Heat Transfer
• Publishing year: 2014
• Language: English
• Publication/Series: Journal of Heat Transfer
• Volume: 136
• Issue: 5
• Links: http://dx.doi.org/10.1115/1.4026370
• Document type: Journal article
• Publisher: American Society Of Mechanical Engineers (ASME)
• Topic: Energy Engineering
• Status: Published
• Research group: heat transfer
• ISBN/ISSN/Other: ISSN: 0022-1481