Two Phase Cooling Technologies for Electric Weapon Platforms

Thermal management is critical for electric weapons on tactical military platforms. These systems pose unique challenges in that the cooling system must dissipate high heat fluxes over large surface areas with limited heat rejection, while functioning in harsh operational environments. Effective two-phase cooling techniques with high-heat transfer rates and low coolant flow rates must be combined with energy storage and dissipation techniques which enable high-energy lasers on compact tactical platforms. In the Phase I feasibility study, an evaluation was performed comparing closed cycle water micro-channel technology, closed cycle two-phase evaporative spray cooling (ESC) technology, and open cycle ESC technology. The study revealed that micro-channel systems are not practical for military tactical platforms, and is one of the limiting factors for the deployment of high-energy lasers (HELs) on these platforms. The Phase I feasibility study has established that ESC, thermal energy storage (TES) and refrigeration are the key technologies that enable a closed cycle cooling system for a 100 kW diode pumped solid-state laser (DPSSL) on a compact tactical platform. The Phase I study also showed that open cycle ESC systems offer a compact solution for lasers with short operation times (< 90 seconds), but are not practical for longer duration The primary focus for the Phase II effort is the development of prototype system that validates these key technology areas. The prototype unit will show scalability of ESC cycle design to support 100 kW DPSSL system while addressing operational "real-environment" characteristics typical of tactical platforms. The ESC technology and systems being developed by RTI under this SBIR effort can provide the DoD and the HEL community with an enabling thermal management capability that works synergistically with air, ground and sea tactical platforms.