High Performance Heat Storage and Dissipation Technology

Abstract

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.

Numerical analysis of a latent heat thermal energy storage system under partial load operating conditions

“…In this temperature range, LHTES systems are typically applied in concentrating solar technologies associated with small size Organic Rankine Cycles (ORCs) [11][12][13] or industrial waste heat recovery systems [14]. Other applications are in solar cooling systems with absorption chillers [15], PAFC fuel cells [16], heat recovery in metal hydride hydrogen storage systems [17] in the food, beverage, transport equipment, textile, machinery, pulp and paper industries and drying of agricultural products [18]. To accomplish the purpose of the present study, a vertical concentric tube heat exchanger was selected as LHTES system based on the configuration of a prototype used for experimental tests at the University of Lleida (Spain) [19].…”

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…”