Experimental study of a heat exchanger for an in-flight oxygen collection launcher

In the scope of an ESA-funded theoretical and experimental study (in the GSTP3 program) on heat exchangers intended to provide in-flight oxygen collection capability to a reusable or a semi-reusable TSTO launcher with an oxygen collection phase in supersonic cruise, two subscale models of an air-hydrogen precooler and a test set-up are currently being developed in Belgium and in Spain. The vehicle we foresee for this application is described in previous conference papers as well as the work on our ESA-funded airborne air separator, which is the other critical element of the oxygen collection plant. This current paper is concentrating only on the theoretical but mainly the technological and experimental aspects of such an air precooler.
The experimental and technical aspects include choices and main trade-offs that have had to be made during the design process by the different partners (Techspace Aero, von Karman Institute, Iberespacio, University of Liège, Royal Military Academy of Belgium and University of Brussels).
After we fixed the requirements at system level and at the precooler level, a simulation work of generic heat exchangers is presented including the problem of frost formation and its influence on the heat exchanger performance. A few advanced heat exchanger designs are analysed resulting in a more detailed parametric and performance analysis of two advanced configurations. A detailed study of the most advantageous heat exchangers materials is shown resulting in the selection of the alloys for the two breadboards.
The manufacturing processes for these two breadboards are defined, based on trials on small scale models inspired from the two technology candidates.
Perspectives are also given for the mechanical and thermodynamic testing of the two breadboards.