Presentation of frictional behavior of micro helical tubes with various geometries and related empirical correlation; an experimental study

Abstract

Abstract This study provides an experimental investigation on the pressure drop and frictional behavior of air flow through helical microtubes with circle, triangle, square and pentagon geometries with different coil diameters. Pressure drop versus flow rate (1, 2, 3, 4 and 5\u202fl/min) has been experimentally investigated for all helical coils. The effect of flow rate, coil diameter and geometry are examined on the pressure drop and friction factor. More applicable and new friction factor correlations in laminar flow regime have been developed in terms of fraction of internal diameter (din) to coil diameter (din/Dc) and the Reynolds number (Re) for all geometries. The comparison between the estimated values of new friction factor correlation and the calculated values of friction factor from general equation showed that the maximum relative errors for circle, triangle, square and pentagon geometries are respectively 9.7%, 14%, 9.47% and 6.4%. Therefore, the correlations can effectively predict the present experimental data.