Adaptive VCS Condenser with Integrated VCHPs for Aircraft Thermal Management

ABSTRACT: Next-generation aircraft are experiencing increasing thermal challenges due to heat generation from avionics, as well as requirements to lift this heat to temperatures high enough for rejection from the platform. Efforts have demonstrated vapor compression systems (VCS) offer a cost-effective cooling solution to lower temperature avionics heat loads. An aircraft VCS is required to utilize all available sinks, including fuel and ram air to effectively manage aircraft thermal loads. However, temperature, flow rate, and pressure of each heat sink vary throughout a mission, meaning that the ability of the VCS to adapt by selecting the most appropriate heat sink will be of critical importance. Advanced Cooling Technologies (ACT) proposes to develop a passive adaptive condenser with integrated variable conductance heat pipes (VCHPs) for an aircraft VCS. The condenser utilizes a highly integrated design that combines a fuel-cooled heat exchanger with an air-cooled heat exchanger. The fuel-cooled heat exchanger adopts a design similar to a typical flatplate heat exchanger but uses high conductivity (HiK) plates as refrigerant and fuel interfaces. The refrigerant is thermally linked to the air-cooled heat exchanger via VCHPs, which passively response to time-variant air flow conditions and controls the heat rejection to the air heat sink. BENEFIT: The potential market penetration point for the proposed technology will likely be the VCS thermal management system in Air Force aircraft. This application presents thermal management requirements that cannot be easily met by the competing technologies. For the military market, the ultimate customer is the DOD. The direct customers for the proposed technology are the defense systems OEMs. Outside of the military market, the commercialization strategy for this technology covers multiple thermal management markets where the VCHPs and HiK plate can be utilized. The proposed HiK plate with embedded VCHPs, as a stand-alone technology, can be utilized in many military, aerospace and commercial electronics cooling applications that require a tight temperature control and an isothermal cold plate, such as electronics in NASA Mars Exploration Rover WEB or NASA's Scientific Balloons. One of the commercial applications for VCHP heat exchangers are fuel cell reformers where operating temperature of the reactors must be closely controlled to maintain their chemical equilibrium, despite changes in the fuel cell electrical load and the resulting changes in reactant flow rates. A VCHP heat pipe heat exchanger can passively adjust the heat removed, and maintain the feed streams and the output stream at a constant temperature.