Metal Hydride Heat Storage Technology for Directed Energy Weapon Systems

Abstract

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.

Catalytic influence of Ni-based additives on the dehydrogenation properties of ball milled MgH2

“…6 However, they also offer significant challenges to be overcome. First, we note that not all metal hydrides have high-energy storage capacities (cf., LaNi 5 H 6 as shown in Table I).…”

“…First, we note that not all metal hydrides have high-energy storage capacities (cf., LaNi 5 H 6 as shown in Table I). In fact, some well-known intermetallic metal hydrides have been studied recently for reversible and reasonably fast thermal storage, 6 but the low thermal energy density of such "classical" hydrides renders them poorly suited for high-density thermal storage. However, some metal hydrides do offer exceptionally high TES density.…”

Effects of Titanium-Containing Additives on the Dehydrogenation Properties of LiAlH4: A Computational and Experimental Study

“…An alternative method of TES is thermo-chemical storage, in which materials absorb and release heat during a reversible endothermic/exothermic reaction. Thermo-chemical storage materials can exhibit an order of magnitude greater thermal storage density (on a mass basis) when compared to PCMs. , Prototype thermo-chemical storage systems based on the highly endothermic (exothermic) dehydrogenation (hydrogenation) reaction of metal hydrides have already been demonstrated. ,, However, these initial systems are limited in their utility due to their reliance on low H 2 -content Ni-based hydrides with resulting low thermal storage density (e.g., Ca 0.2 M 0.8 Ni 5 H 6 , contains <1.5 wt % H 2 , storing 173 kJ/kg) − or high-temperature dehydrogenation reactions (e.g., >300 °C for MgH 2 ) . In addition to TES systems, metal hydrides are attractive for use in high capacity hydrogen storage devices because of their ability to store hydrogen in compact volumes .…”

“…This work focuses on the dehydrogenation behavior of lithium Alanate (LiAlH 4 ), due to its outstanding H 2 storage capacity (10.6 wt % total), and relatively low temperature of spontaneous decomposition (7.9 wt % given off below 250 °C) when compared to other hydrides. ,− The dehydrogenation of pure bulk LiAlH 4 is believed to occur in the following steps, as shown in eqs 1– LiAlH 4 ( s ) → LiAlH 4 ( l ) LiAlH 4 ( l ) → 1 3 Li 3 AlH 6 ( s ) + 2 3 Al ( s ) + normalH 2 ( g ) .25em [ 5.3 wt % ] 1 3 Li 3 AlH 6 ( s ) → LiH ( s ) + 1 3 Al ( s ) + 1…”