Experimental verification of ultra-high-performance, advanced-propulsion heat exchangers

High-performance compact heat exchangers are a critical technology for many advanced air-breathing propulsion systems, including liquid air cycle engines (LACE). In order to make these systems practical, large performance gains over current state-of-practice ground-based heat exchangers must be realized to reduce heat exchanger mass. Theoretical investigations have predicted these gains to be achievable through advanced geometry and operation at very high Reynolds numbers. This paper presents the initial results of experimental studies at the University of Illinois, designed to verify these predicted gains. The experimental apparatus used to test heat transfer performance is based on the naphthalene sublimation mass transfer technique. Experimental results are presented for Reynolds numbers as high as 100,000 - more than ten times higher than any published study to date. Comparison of the results to previous predictions for high-Re heat exchanger performance shows order-of-magnitude increases in the heat transfer coefficient, suggesting that ultra-high performance compact heat exchangers are achievable for propulsion applications.