Description: Modern high efficiency gas turbine engines typically operate with hot section temperatures so high that metal parts in those areas need to be cooled to maintain strength and life properties. A well-established approach to this bleeds a portion of the compressor discharge air to flow through and over turbine parts. As engine compressor pressure ratios continue to increase, the temperature of this compressor discharge air also increases, to the point that the cooling air itself needs to be cooled. Micro Cooling Concepts is involved in developing a concept for a heat exchanger co-located/integrated near the point of fuel injection in order to provide cooled cooling air. The main advantages of this concept are the minimization of the amount of heated fuel between the heat exchanger and fuel injector tip such that the fire danger from leaking tubing is eliminated, and the ease of delivering cooled cooling air to the secondary air circuit. Additionally, the modular concept distributes the heat exchange function, allowing for easy replacement of an individual heat exchanger module. For this program, high temperature materials will be used for fabrication using Micro Cooling Concepts' laminated foil construction approach. This effort supports the NASA goal of improving aeropropulsive efficiency through reduced fuel burn and increased cycle temperatures, specifically by enabling very high turbine cooling effectiveness.

Benefits: A reduction in the temperature of available cooling air would provide additional heat sink, thereby enabling use of higher combustion temperatures. The benefits of such a concept include reduced fuel burn and the accompanying reduction in CO2 emissions, in alignment with NASA's goals, with accompanying minimal fire risk. This technology would be applicable to any NASA air-breathing fuel-based propulsion systems where available cooling air temperatures are currently too high to reach the desired performance goals.

The ability to provide cooled cooling air with minimal fire risk offers a compelling value proposition to turbine manufacturers and their clients. A major engine manufacturer has interest in incorporating the proposed concept into future civil and defense gas turbine engine products that currently show benefits from fuel-cooled cooling air. The designs proposed are inherently compatible with Micro Cooling Concepts' existing production line, enabling arrangements such as building the components under contract or licensing the IP to the engine manufacturer and/or their suppliers.