Lightweight Titanium Heat Exchangers

The evolution of materials in advanced aircraft continues and there is emerging interest from the U.S. Air Force to move titanium alloys into heat exchangers for advanced aircraft. Titanium substitution will lower the weight of nickel base alloy heatexchangers by over 30%, leading to increased fuel economies and performance. The proposed Phase II effort will select a typical aircraft stainless steel bleed air heat exchanger, making the appropriate design and manufacturing changes to substitutetitanium for stainless steel or nickel based alloys. In Phase II, MRi and Lytron, a heat exchanger manufacturing partner, propose to develop braze joining procedures and integrate processes into designs able to fabricate thin sheet titanium plate-fin heatexchangers, similar to those used in stainless steel or aluminum heat exchangers. Phase II work will aim at a development of specific heat exchanger designs, subsequent optimization of braze filler metals, and development of braze cycles and proceduresconsistent with manufacturing methods. Issues such as braze joint geometry, placement of braze filler metals, braze temperatures, braze fixturing and braze conditions on the final braze strength will be investigated. MRi and Lytron will develop designs,investigate fabrication methods and subsequently make up to four prototype units for test at the end of Phase II. Upon completion of these tests, is it expected that the titanium heat exchanger design and manufacturing procedures would be tested andvalidated in preparation for possible flight certification programs.