Dual Mode Waste Heat Scavenging System for Unmanned Aerial Vehicles

In a typical unmanned aerial vehicle a significant proportion of the propulsion system power output is converted to electrical power to operate payload and avionics hardware. The removal or significant reduction of the growing electric power generation load from the engine could lead to extended mission endurance by reducing the fuel burned for electrical power production, and by reducing the mass of both primary and backup power conversion/energy storage systems. We propose to assess the feasibility of reducing engine power generation loads and increasing system endurance by scavenging waste heat from vehicle subsystems using thermoelectric generator technology. An innovative solution is proposed whereby energy harvested from both the high temperature heat source of the engine exhaust stream is combined with energy harvested from the comparatively low temperatures of the liquid streams used to cool the onboard electronics and potentially engine components. To efficiently combine these multiple power sources, power management electronics are used to process scavenged electrical power and manage temperatures in the liquid coolant streams to maintain the electronic equipment operation within prescribed limits. The innovation proposed here is a conformable system architecture that is both modular and scalable for use over an extended range of unmanned system applications.