Numerical and experimental study of heat-and-mass transfer processes in two-stage metal hydride hydrogen compressor

Metal hydride hydrogen compressors for energy storage systems: layout features and results of long-term tests

“…Modelling of heat transfer performance of MH beds on the basis of the AB 5 -type alloys showed that externally heated and cooled cylindrical beds with a high length-to-diameter ratio is an optimal solution due to (i) high heat exchange area between the MH and the heating/cooling fluid, (ii) simplicity and lower cost and (iii) less pronounced reduction of hydrogen storage capacity at the same dimensions as compared to the solutions with internal heat exchangers [21]. According to the modelling results verified by experiments [22], the externally heated and cooled cylindrical stainless steel containers, about 20 mm in the internal diameter and about 800 mm in the length, filled by the selected AB 5 -type materials, are characterised by satisfactory H 2 absorption/desorption (H 2 charge/discharge times shorter than 20 min), if averaged heat transfer coefficient between the MH container walls and the heating/cooling fluid is about 500 W m −2 K and higher. In this case, hydrogen absorption/desorption dynamics is almost completely determined by the heat transfer in the MH bed (effective thermal conductivity about 1.5 W m −1 K without heat transfer augmentation).…”

“…As it can be seen in figure 1, the cycle productivity of two-stage H 2 compression utilising these AB 5 -type alloys (∼80 NL H 2 /kg) is limited by hydrogen transfer from stage 1 to stage 2 at P M ≈35 atm. This drawback was, however, mitigated by the increase of the amount of the MH material on stage 1 of the hydrogen compressor by 20%-25% in the weight as compared to stage 2 [19,20,22].…”

“…In this case, hydrogen absorption/desorption dynamics is almost completely determined by the heat transfer in the MH bed (effective thermal conductivity about 1.5 W m −1 K without heat transfer augmentation). Further increase of the effective thermal conductivity (up to 12 W m −1 K) was achieved by a placing the MH powder into porous high thermally conductive matrix (copper foam) [22]. The latter solution was used in the TSC2-3.5/150 model.…”

“…The latter solution was used in the TSC2-3.5/150 model. The optimal two-stage hydrogen compression (3.5-150 atm) performance of such layout of the MH container was achieved at the duration of the heating (140°C-160°C) and cooling (20°C-40°C) between 10 and 24 min (full compression cycle duration 20-48 min) [19,22].…”

“…This work summarises the results of joint development, by SKTBE and IPCP, and long-term operation of two models of two-stage metal hydride hydrogen compressors, TSC1-3.5/150 and TSC2-3.5/150. Further details have been published in [16][17][18][19][20][21][22].…”