A novel type of falling film heat and mass exchanger: spirally wound fin tube.

A novel type of falling film heat and mass exchanger is presented where the working fluid flows as a thin film on a spirally wound fin formed on either the inside or outside wall of a circular base tube heated by a heat carrier fluid flowing on the other side. The hydrodynamics and the heat transfer were studied for two different types of spiral fin heat exchangers: a graphite tube with a spiral fin on the outside and a brass tube with the spiral fin on the inside. The latter is built up of individual discs of which a given section is cut out. The discs are assembled, turning one with respect to the other in order to make a "spiral staircase". These spiral fin tubes were studied with different geometric parameters.