N2 - Free convection is one of the heat transfer modes which occurs within the
heat-treated bundles of steel rectangular section. A comprehensive study
of this phenomenon is necessary for optimizing the heating process of this
type of charge. The free convection intensity is represented by the
Rayleigh number Ra. The value of this criterion depends on the following
parameters: the mean section temperature, temperature difference within
the section, kinematic coefficient of viscosity, volume expansion
coefficient and the Prandtl number. The paper presents the analysis of the
impact of these factors on free convection in steel rectangular sections.
The starting point for this analysis were the results of experimental
examinations. It was found that the highest intensity of this process
occurs for the temperature of 100°C. This is mainly caused by changes in
the temperature difference observed in the area of sections and changes in
kinematic coefficient of viscosity of air. The increase in the value of
the Rayleigh number criterion at the initial stage is attributable to
changes in the parameter of temperature difference within the section.
After exceeding 100°C, the main effect on convection is from changes in
air viscosity. Thus, with further increase in temperature, the Rayleigh
number starts to decline rapidly despite further rise in the difference in
temperature.
JO - Archives of Thermodynamics
L1 - http://journals.pan.pl/Content/94778/PDF/07_paper.pdf
L2 - http://journals.pan.pl/Content/94778
IS - No 3 September
EP - 121
KW - free convection
KW - Rayleigh number
KW - section bundles
KW - effective thermal conductivity
KW - heat treatment
ER -
A1 - Wyczółkowski, Rafał
PB - The Committee on Thermodynamics and Combustion of the Polish Academy of Sciences
JF - Archives of Thermodynamics
SP - 105
T1 - Analysis of components effecting free convection intensity in steel rectangular sections
UR - http://journals.pan.pl/dlibra/docmetadata?id=94778
DOI - 10.1515/aoter-2015-0024