Energy Rejection System for Very High Altitude Aircraft

High efficiency engines that reject waste heat to the atmosphere are needed for high altitude (85,000-100,000 ft), low speed aircraft that are envisioned for DoD applications. Often, a heat exchanger is required to reject the waste heat. The challenges of heat rejection are associated with the fact that because the density of the high altitude air is low and the velocity of the aircraft is low (to reduce drag), the mass flux of the air through the heat exchanger is quite low. It is a significant design challenge to build a heat exchanger that can simultaneously handle the large volume flow rates typical of high altitude scenarios, the low available pressure drop, and the need to be compact and lightweight. Mezzo builds micro tube heat exchangers that provide excellent heat transfer/volume and heat transfer/weight ratios, low pressure drop and ease of manufacture. Mezzo will design, build, and test a heat exchanger in an environment closely simulating flight at 85,000 ft. The program will provide quantified performance metrics (heat transfer and pressure drop) that will be needed to design full scale Mezzo heat exchangers for use in full scale, complete systems.