Evaluation of Various Energy Storage Options for the Internal Thermal Loads of a Non-Airbreathing Hypersonic Vehicle

Energy storage within hypersonic aircraft is becoming increasingly important with the development of more sophisticated electronic components and is an integral piece of expanding their overall capabilities. Hypersonics not only produce large external thermal loads, but also an abundance of internal thermal loads from components such as power electronics, avionics, and batteries. Additionally, limited volume within such vehicles introduces additional constraints. Thus, having efficient heat sinks that are capable of storing much of these heat loads is imperative. Passive thermal management systems, i.e., heat sinks, are preferable in most applications because they do not require power input to operate, and they are typically smaller than active systems such as coolant loops. In identifying and developing heat sinks with increased energy storage capability, an exhaustive search of available phase change materials (PCMs) is conducted. PCMs have been used in hypersonic vehicles in the past as a means of energy storage. Additionally, the use of energy-consuming endothermic reactions is considered. An innovative PCM-endothermic reaction hybrid approach is also developed. Both thermodynamic and transient/quasi-stationary models are developed for each of these proposed heat sink technologies. Prototypes are then developed for the best candidates to validate the models and draw conclusions on each heat sink's performance. Both the thermodynamic modeling and experimental results presented in this paper suggest that PCMs, endothermic reactions, and, especially, the hybrid system show greater energy storage capabilities than what is being used in hypersonic vehicles currently.