14000 brazed joints on heat exchanger for mobile gas turbines!

heat exchanger /MTU Aero Engines

It was a great challenge, even for the brazing specialist from Listemann AG, when they were entrusted by MTU in Munich in 2002 to develop a robust brazing process for industrial manufacturing of heat exchangers for mobile gas turbines.

This heat exchanger should increase the efficiency of turbines for heavy land vehicles and aircrafts, in order to safe a substantial amount of fuel. In essence the heat exchanger consists of 7000 thin walled, profiled tubes being brazed to the larger air inlet and outlet tubes. Besides the huge number of brazed joints which have to be leak-tight the major challenge were wide and irregular gaps which can result in brittle phase formation when brazing with nickel based brazing alloys.

To manage this particular constraint an in-depth knowledge of material properties, heat treatment technologies and brazing processes is required. This mix of competencies is one of Listemann's strength and resulted, after a fairly short development time of one year, in the production of 50 prototypes, which demonstrated the series-production readiness of Listemann brazing technology.