||Wright-Patterson AFB, OH 454337542
Many high power density systems, including power electronics, lasers, and microwaves often operate cyclically and intermittently, generating enormous amounts of waste heat in a short period of time. Any thermal management system (TMS) designed for the peak thermal load will be over capacity on average, resulting in a larger, heavier TMS. An intermediate thermal energy storage system would store the peak thermal load and allow the heat to be rejected at an average rate, resulting in a smaller and lighter heat rejection system.
Many mechanisms are available to store heat at a near constant temperature, including latent heat of phase change (e.g., melting of solid like paraffins, vaporization of liquid like water and ammonia), chemical reactions (e.g., endothermic reaction of metal hydrides [MH]), and adsorptions (e.g., zeolite). Each approach has its advantages and disadvantages. The disadvantages pose a great challenge when they’re packaged into an airborne TES system. For example, paraffin based PCMs offer excellent operating temperature ranges, yet they have very low thermal conductivity and relatively low latent heat (heavy). Vaporization of water or ammonia offers a magnitude of higher mass energy density but the volume of the vapor is not feasible for airborne application (big). While the temperature range and mass energy density of metal hydrides are desirable, their endothermic reaction product, hydrogen gas, is not. Another severe application issue is the recharging of MH. Adsorption based TES also has problems with its operating temperature and recharging.
This research focuses on thermal energy storage materials and technologies. Specific technical goals include high thermal energy mass and volume density, high heat transfer rate (high effective thermal conductivity), and reversible (rechargeable TES) and near constant temperature (i.e., sensible heat approaches will not be considered).
Kota K, et al: Journal of Thermophysics and Heat Transfer (22)4: 2008
Thermal energy storage; Phase change material; TES; TM; PCM; High rate thermal energy storage;