The whole length of the heat transfer section was thermally insulated to minimize the heat exchange to the environment. Both the wall and the inlet and outlet fluid temperature were measured through 40 type T thermocouples, previously calibrated and connected to a multichannel ice point reference, type KAYE K170-50C. Regarding the wall temperature the sensors were attached at different circumferential locations to the external tube’s surface and at different axial locations along the heated section. In particular, the thermocouples were placed along the external and internal side of the coil in order to investigate the distortion over the cross section induced by the centrifugal force to the velocity and then to the temperature profile. Regarding the corrugated wall tubes the temperature probes were placed externally on the crest of the corrugation at different circumferential locations. The inlet temperature was measured by a thermocouple probe placed on the tube’s wall upstream the starting heating section.