An experimental study of convective heat transfer from extruded type helical finned tubes

The hydraulic–thermal investigation were carried out for nine different staggered bundles made of bimetallic helical high finned extruded type tubes under the conditions of air flow perpendicular to horizontal staggered banks of tubes. For the flow in tubes water, or for the temperatures up to 310 °C, oil (Iterm 6Mb) was used. For the sake of determining the value of heat transfer coefficient (HTC) the use was made of the -NTU method. Correlations have been worked out allowing for the effect of geometric parameters and tube bundles on HTC and air pressure drop. The gas-side HTCs obtained, were higher by approximately 20% with respect to the correlations presented in the literature. These coefficients were determined at the pressure drops, close to those near in literature.