Predictive tool for estimation of convection heat transfer coefficients and efficiencies for finned tubular sections

Fins or extended surfaces are widely used to increase the air side heat transfer rate in various heat exchange applications. In this paper, firstly, an attempt has been made to formulate a novel and simple-to-use correlation for the prediction of efficiencies for uniform thickness finned tubular sections as well as fin tip temperature for wide range of conditions (covering finned pipe diameter to pipe diameter ratios of up to 3). Secondly, another simple correlation is developed to approximate external convection heat transfer coefficients for nominal pipe size (NPS) steel pipes of 75, 100, and 150 mm arranged in staggered rows surrounded by combustion gases for temperature up to 600 °C and gas mass flow rates of up to 3 kg/(m2 s). A simple interpolation formula generalizes this correlation for wide range of steel pipes. Average absolute deviations between the reported data and the proposed correlations are found to be around 1% demonstrating the excellent performance of proposed correlation. The tool developed in this study can be of immense practical value for engineers and scientists to have a quick check on the efficiencies for uniform thickness finned tubular sections as well as external convection heat transfer coefficients for various steel pipes arranged in staggered rows and surrounded by combustion gases flowing externally to heat a liquid in a pipe at various conditions without opting for any experimental measurements. In particular, practice engineers would find the predictive tool to be user-friendly with transparent calculations involving no complex expressions.