ISSN Online: 2688-7231
ISBN Online: 978-1-56700-524-0
Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India
Thermal Performance Comparisons of ECT and Helical-Coiled based Metal-Hydride Reactor
The design of metal hydride-based reactor plays a prominent role in studying metal hydride-based hydrogen storage systems. Metal hydride-based hydrogen storage systems (MHHSS) generate heat while absorption of hydrogen, while the required heat is supplied during the desorption of hydrogen. Therefore, efficient heat removal/supply is the preliminary requirement of such systems. A systematic study is presented to compare the hydrogenation and dehydrogenation capacity of the embedded cooling tube (ECT) and helical coiled based reactor geometry using COMSOL Multiphysics 5.3a. The metal hydride (MH) alloy used in the study is 20 kg of MmNi4.6Al0.4 in both designs. The heat transfer area at the tube-bed interface is kept constant in both the reactor designs. The present study is conducted by varying different parameters like hydrogen supply pressure, hydrogen desorption pressure and heat transfer fluid (HTF) temperature. At 30 bar hydrogen supply pressure, complete hydrogen absorption took place after 1360 s for helical coiled based reactor whereas it took 3950 s for ECT based reactor. The helical coiled based reactor took 25% lesser desorption time than ECT based reactor at 1 bar when the initial bed temperature was 323 K. From the study, it is observed that helical coiled based MH reactor proves to be a better MH reactor. This is due to the developed secondary circulation of the HTF through the helical tube and the superior convective heat transfer coefficient.