1. Definitions

1.1 Principle of the flow-through tube

The flow-through tube is a new electrothermal technique in terms of its applications, but old and very simple in terms of its principle. It involves energizing the pipe containing the fluid to be heated. The passage of a current through the tube generates heat by the Joule effect. Heat transfer from the tube to the fluid is essentially by forced convection, via an exchange surface: the tube's inner wall.

The tube fulfils three functions simultaneously:

• hydraulic guide for the fluid, which is its primary function;

• electrical resistance ;

• heat exchange surface.