Experimental correlation for external forced convection in non-standardized finned tubes perpendicular to the flow

Abstract

Few correlations for forced convection are available and those that exist, some for more than half a century, are for a limited class of tubes and fins standardized in a profile that is difficult to manufacture as they are not found commercially in most countries. However, such correlations do not apply to different tube profiles currently available in many countries, which causes difficulties in designing heat exchangers that require finned surfaces. This work proposes an experimental correlation for convection heat transfer in non-standardized finned tubes subject to perpendicular air flow. Different tube samples are tested in an open circuit wind tunnel. Reynolds numbers are obtained by varying the flow velocity. The fluid flow affects the temperature field in the fluid, including the temperature of the tube surface, and as a consequence the convective heat transfer coefficient. Values of Nusselt and Reynolds numbers are plotted to determine the unknown parameters of the correlation through linear regression and optimization. A comparison between the experimental results and results from the proposed correlation shows that the errors are within the range found in the literature. The proposed correlation is valid for the flow conditions stipulated in this work, which covers most industrial heat exchanger applications.