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Directed Energy Weapon (DEW) systems in a pulse operation mode dissipate excessively large, transient waste heat because of their inherent inefficiencies. The heat storage system can store such a pulsed heat load not relying on oversized systems and dissipate the stored heat over time after the pulse operation. A compressor-driven metal hydride heat storage system was developed for efficient, compact heat storage and dissipation of the transient heat from the DEW systems. The greater volumetric heat storage capacity of metal hydride material was realized into more compact design than conventional Phase Change Material (PCM) systems. Other exclusive advantages of the metal hydride system were fast thermal response time and active heat pumping capability required for precision temperature control and on-demand cooling. This paper presented the operating principle and heat storage performance results of the compressor-driven metal hydride heat storage system through system modeling and prototype testing. The modeling and test results showed that the metal hydride system can store the average heat of 4.4kW during the heat storage period of 250 seconds and release the stored heat during the subsequent regeneration period of 900 seconds.

High power solid state laser systems operating in a pulse mode dissipate the transient and excessively large waste heat from the laser diode arrays and gain material. The heat storage option using Phase Change Materials (PCMs) has been considered to manage such peak heat loads not relying on oversized systems for real-time cooling. However, the PCM heat storage systems suffer from the low heat storage densities and poor thermal conductivities of the conventional PCMs, consequently requiring large PCM volumes housed in thermal conductors such as aluminum or graphite foams. We developed a high performance metal hydride heat storage system for efficient and passive acquisition, storage, transport and dissipation of the transient, high heat flux heat from the high power solid state laser systems. The greater volumetric heat storage capacity of metal hydrides than the conventional PCMs can be translated into very compact systems with shorter heat transfer paths and therefore less thermal resistance. Other exclusive properties of the metal hydride materials consist of fast thermal response and active cooling capability required for the precision temperature control and transient high heat flux cooling. This paper discusses the operating principle and heat storage performance results of the metal hydride heat storage system through system analysis and prototype testing. The results revealed the superior heat storage performance of the metal hydride system to a conventional PCM system in terms of temperature excursion and system volume requirement.

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