Aircraft Based Pulsed Power System Thermal Management Options with Energy Storage

Abstract

The impact of thermal management related conceptual improvements including thermal energy storage on the overall performance of thermal management system (TMS) for a pulsed power platform was assessed with the help of a general thermodynamic analysis. The power system, for which the TMS is being analyzed, essentially consists of a prime power source, electrical power generator, power conditioner, pulsed power source and pulsed power processor. The TMS analysis corresponds to a notional aircraft mission, with the turbo-shaft engine operating at a fixed altitude. The thermal load from various system components is collected by the same coolant loop, and then rejected to ambient air in a ram air heat exchanger (RAHX). The acquisition of heat from the pulsed power tube, the major contributor to the heat load, is assumed to be accomplished by a single-phase, sub-cooled flow boiling process and from the remaining components by forced convection. As an alternative to using the sensible heat of water to acquire and dispose of waste heat, using the latent heat of fusion of phase change materials (PCM) for thermal energy storage (TES) has been explored to some detail in this analysis. Standard air properties at the mission altitude and designated air speed have been used in the design of the RAHX. Three closed-loop cooling schemes have been considered, setting up the flow conditions of the coolant fluid transporting the heat from the sources to the TES as well as sizing of the PCM cells. Results show that for both the fin-tube and layered plate-fin RAHX configurations, raising the hot fluid operating temperature results in considerable system mass saving. It has also been found that operating the RAHX continuously, with a “balanced” heat load shared between the TES and the RAHX in the proportion dictated by the duty cycle (DC) of operation, leads to considerable savings in RAHX, and hence TMS, mass and size.