The widespread use of the helicoidal pipes in heat exchangers for air conditioning and refrigeration systems, chemical reactors, and nuclear power plants is due to their heat transfer high efficiency and their compactness. Depending on specific applications of these components, for adequate design purposes, it is important to have a full knowledge of fluid dynamics behavior, both in single and in two phase flow conditions. In fact, as it is well known, the secondary flow due to the centrifugal force in the cross section of the helicoidal pipes is a significant factor affecting the thermal-fluid dynamic
