The stringent mass targets of the Hermes spaceplane require the design of extremely compact plate & fin heat exchangers, hence with a very low fin height, operating at low Reynolds numbers. These parameters, low Re (10-500 range) and low fin height (0.8 mm), have so far been little investigated and never applied to heat exchanger hardware development in Europe. Moreover, almost no relevant test data is available in the public domain, and what exists has been obtained from tests with gases rather than liquids.
A programme, involving the design, manufacture and performance testing of a HX representative of the Hermes Interloop Heat Exchanger requirements, has been set up in order to explore manufacturing difficulties associated with such low height fins and to verify by test the fin thermo-hydraulic performance.
These tests have been carried out with water (and their results are thus directly applicable to the most common fluids employed in spacecraft active thermal control) and have explored the range of low Reynolds numbers which are also directly applicable to the design of present spacecraft heat exchangers, and for which no test data has previously been published.
This paper describes in detail the Technology Demonstrator design criteria, the test set-up and the test results obtained.