High pressure thermal hydrogen compression employing Ti_1.1CrMn metal hydride material

Abstract

The use of Ti 1.1 CrMn metal hydride material in a thermal hydrogen compression system is investigated. The thermodynamic properties of the material, initially synthesized and annealed at 900°C for 48 h (for quantities on the order of 10 kg), are assessed performing pressureconcentration-temperature equilibrium tests for hydrogen absorption and desorption at pressure up to about 900 bar. Results show flat plateaus and reduced hysteresis. The calculated absorption enthalpy and entropy are 20.55 ± 0.13 kJ mol H2 1 and 102.16±3.00 J mol H2 1 -K −1 respectively. The desorption enthalpy and entropy are 22.89±0.45 kJ mol H2 1 and 107.80±10.45 J mol H2 1 -K −1 , respectively. The metal hydride achieves a weight capacity of approximately 1.8% at room temperature and maintain an approximately constant weight capacity during the cycling testing. This makes the material a suitable candidate for high pressure hydrogen compressors, achieving pressures on the order of 450 bar at temperatures of approximately 140°C. The same material composition is synthesized at laboratory scale quantities (on the order of 50 g), applying a modified annealing procedure (1200°C for 240 h). This allows higher operating pressures to be achieved, but the modified annealing process also produces (at least) an additional phase, namely the C15 Laves phase, present in the material along with the C14 Laves phase. Consequently, two pressure plateaus are present at each operating temperature, reducing the effective material weight capacity available for the compression application. A two-stage hybrid compressor concept is also presented, with the thermal hydride compressor paired with a lower pressure electrochemical unit. In principle, the system can compress hydrogen with a compression ratio of 45 from 10 to 450 bar without any external thermal input and recovering the electrochemical unit waste heat to drive the thermal stage.

Thermally driven hydrogen compression using metal hydrides

“…Most of the articles related to hydrogen compression materials and published since 2015 consider multi‐component C14‐AB 2±x intermetallics where A = Ti or Ti + Zr and B = Cr, Fe, V, Mn 27‐38 . Certain attention has been paid to BCC alloys in V–Ti–Cr system, 39‐43 multiphase C14 + BCC Ti–V–Mn alloys, 44 as well as AB 5 ‐type intermetallics 22,45,46 .…”

“…Most of the articles related to hydrogen compression materials and published since 2015 consider multicomponent C14-AB 2±x intermetallics where A = Ti or Ti + Zr and B = Cr, Fe, V, Mn. [27][28][29][30][31][32][33][34][35][36][37][38] Certain attention has been paid to BCC alloys in V-Ti-Cr system, [39][40][41][42][43] multiphase C14 + BCC Ti-V-Mn alloys, 44 as well as AB 5type intermetallics. 22,45,46 Practically all the studies consider equilibrium pressure-composition-temperature (PCT) characteristics of hydrogen compression alloys when interacting with H 2 gas.…”

“…Straightforward realization of this approach implies direct measurement of the pressurecomposition isotherms at T L (absorption) and T H (desorption) followed by the estimation of ΔC at the specified P L and P H ; see, for example. 32,35,38 However, a more flexible and less time-and resource-consuming procedure is in the use of a modeled PCT diagram covering relevant pressure-temperature range. 25,26,51 The applied PCT model should adequately describe the abovementioned features (plateau length, slope, and hysteresis) in the whole range of temperatures and hydrogen pressures and, as possible, to realistically extrapolate the experimental PCT data out of the ranges where they were collected for the model calibration/refinement of the coefficients by fitting.…”

Solid-State Hydrogen Storage for a Decarbonized Society

“…Using this method, metal hydrides are placed in a standard high-pressure tank. Such a concept has been pursued by a number of companies, including Toyota Motor Company, which developed a 7.3 kg hydrogen tank based on the alloy Ti 1.1 CrMn [60] that could be refilled to 80% of its capacity in only 5 min [57]. Unfortunately, using such alloys inside the high-pressure tank results in a significant increase in vehicle weight (compared to high-pressure tank vehicles), which can only be partially offset by using higher-cost, lighter-weight materials for the vehicle's other components.…”

Thermodynamic features of metal hydride thermal sorption compressors and perspectives of their application in hydrogen liquefaction systems

“…Reversible intermetallic hydrides are able to repeatedly absorb and desorb gaseous hydrogen at different pressures, which depend on the temperature potential of the released/absorbed heat [2][3][4][5]. This feature forms a basis of thermo-chemical technology of hydrogen compression realised in a thermal sorption compressor (TSC) utilising metal hydrides (MHs), in which exothermic and endothermic processes of H 2 absorption and desorption in the MH are similar to processes of suction and discharge in a mechanical compressor [1,[6][7][8][9][10][11][12][13]. As a rule, the development of an MH TSC is preceded by its modelling aimed at the determination of the number of H 2 compression stages including proper selection of the MH materials to provide compression from p 1 = p min to p 2 = p max (specified by a customer) over an available temperature range, T 1 = T min … T 2 = T max [13][14][15][16], as well as optimisation of heat transfer performance in the MH beds in MH containers for hydrogen compression (generators-sorbers) to improve the dynamic characteristics of the TSC [14,[16][17][18].…”