Flow characteristics of spirally coiled tubes in terms of their secondary flow and pressure drop are investi-gated. Four spirally coiled tubes with different curvature ratios; under constant wall temperature, are numerically simulated. In the system, water is entering the innermost turn and flows out at the outermost turn. To build the numer-ical model, a finite volume method with an unstructured grid system is employed for solving the Navier-Stokes equa-tions system. Correspondingly, the standard k–ε turbulence model is employed to predict the flow development. Here, the mass flow rate in the spirally coiled tube is set to vary within the range 0.03-0.12 kg/s. The numerically ob-tained data of the pressure drop in the spiral coils are put side by side the experimental data reported in the literature. A close agreement is observed between the experimental data and the results of this study. Based on the results, a new correlation is proposed for predicting the pressure drop in horizontal spiral coils.
