Publication Date


Document Type


Committee Members

Rory Roberts (Advisor), Mitch Wolff (Committee Member), Zifeng Yang (Committee Member)

Degree Name

Master of Science in Mechanical Engineering (MSME)


As technology advances, the abilities of civilian and military vehicles, both air and ground, will undoubtedly increase as well. One of the main areas of improvement is in the electronics area. The new electronics are ever smaller, use ever higher amounts of electrical power, and require ever smaller temperature tolerances. This leads to the problem of effectively managing the increasing thermal loads and temperature tolerances on these systems. One electronic system that causes concern is a high energy pulse system (HEPS). These devices have very high thermal loads (100s of kW). On an air vehicle, where thermal management by legacy methods (i.e. fuel as the heat sink) is already problematic, a HEPS will certainly overload the thermal management system (TMS). HEPS performance must be understood and quantified more accurately to understand the design requirements of a TMS for this device. To aid in this understanding, the HEPS itself and a palletized system to thermally manage the HEPS will be modeled. Previous analysis of a cryogenic palletized HEPS contained a simplified power model for a HEPS that had a set efficiency and always gave a certain amount of optical power out and a certain amount of power dissipated as heat based on that set efficiency. The HEPS model developed and presented takes into account the temperature of internal HEPS components and changes the efficiency accordingly. The HEPS efficiency changes with component temperature to provide a better understanding of the consequences of not thermally managing a HEPS effectively. Along with the HEPS model, a cryogenic-based palletized TMS using Liquefied Natural Gas (LNG) for indirectly cooling the HEPS was modeled. Using LNG as a method of cooling is a possible alternative to using very large legacy systems (fuel as heat sink) to cool a HEPS. The architecture of this palletized system uses LNG to cool the heat loads. The LNG then becomes the fuel for the turbo-generator, which produces electrical power for the HEPS and other pallet systems. The main reason for modeling a palletized system like this is to provide a platform to conduct a comparison test between a constant efficiency HEPS model and a dynamic efficiency HEPS model. This will show whether or not the dynamic efficiency aspects of HEPS operation must be taken into account when designing the coupled TMS architecture. Learning the nuances of HEPS component operation and how the component efficiencies change with temperature will pave the way for future work in designing a TMS capable of keeping these HEPS component temperatures in perfect balance, thus providing a robust, usable, and practical HEPS design.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded