Abstract:
In this experimental study, hydrodynamic and thermally
developing flow associated with mixed convection was
examined in the transitional flow regime for a horizontal
concentric annular passage. The test facility, which consisted of
a counter-flow heat exchanger having an annular diameter ratio
was 0.483 with an inner passage wall diameter of 15.90 mm,
was operated at different degrees of longitudinal Wall
Temperature Uniformity (WTU) for heated flow applications
using a conventional annular inlet geometry type. The degree
of WTU is described in this paper as a ratio of the wall
temperature (value in Kelvin) at the outlet to the wall
temperature (value in Kelvin) at the inlet of the inner surface of
annular passage. Three different degrees of WTUs of 0.99,
0.975 and 0.965 were examined. Critical Reynolds numbers
based on heat transfer were analyzed. It was found that the
degree of WTU have an influence on critical Reynolds number
and the heat transfer coefficient. A model which takes into
account WTU is proposed to predict heat transfer in the
transition regime.
Description:
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.
