Infrared thermography for local Nusselt number estimation of an elliptical fin with a transient method
Résumé
In this paper, a transient method involving an infrared (IR) set-up is used to investigate
local heat transfer distribution over the fin of a staggered elliptical finned tube
heat exchanger assembly. An experimental test bench was designed to record data
during the fin cooling. The procedure of data preprocessing including IR camera calibration
is presented. It allows extracting the temperature field evolution of the fin.
These temperatures feed a numerical model that works with thermally thin material
and takes into account lateral heat conduction and radiation with the surrounding.
The heat transfer coefficient field is determined by integrating the model over time
intervals that depend on space. Distributions of Nusselt number over the fin and
their uncertainties are presented for several Reynolds numbers. The high resolution
of the whole method and set-up allows detecting thermal imprints of developing
horseshoe vortices.