Pressure drop in mini-scale coiled tubing

In the present study, laminar, steady state flow in mini-scale coiled tubes was studied experimentally. Three different tube diameters: 1.59 mm, 1.27 mm and 1.016 mm with different lengths of 1 m and 0.5 m were coiled with different radius of curvature to provide data over a wide range of Reynolds numbers from 5 to 2300. An asymptotic model is developed based on the experimental results to predict the pressure drop increase based on Dean number. The results and simple model are also compared to a well-known existing model for circular tubing. The coiled tube lengths used in this study were long enough to consider the flow to be fully developed. The effects of varying curvature and tube length are also studied. The pitch of the coils is restricted to the diameter of the tube to minimize the effect of coiling. Dean number is used instead of Coiled number (modified Dean number) which allows the results to be expanded to spiral and curved tubing.