Performance investigation of metal hydride based heat transformer

Abstract

Energy is one of the major inputs for the economic development of any country. However, for developing countries energy is essential for economic growth, which calls for the development of clean and sustainable energy source/carrier. Among all the possible options, hydrogen has been considered as a promising clean energy carrier, which is associated with major challenges of its storage and application. Hydrogen can be stored safely in the form of metal hydrides whose formation and decomposition involve high heat interaction, which can be used for the development of thermodynamic systems like sorption heat pumps, which can transform waste heat to useful high‐grade heat. In the present work, the performance of metal hydride based heat transformer (MHHT) is investigated in terms of variation in MH bed temperature and hydrogen interaction between coupled reactors during hydrogen transfer processes, in addition to thermodynamic performance (ie, Coefficient of Performance (COP), heating capacity, and so on) for the operating temperature of T L = 303 K, T M = 383 K, and T H = 423 K. A pair of La 0.9 Ce 0.1 Ni 5 and LaNi 4.6 Al 0.4 is chosen for present study based on author's previous work. In the present study, user‐defined functions are employed in ANSYS Fluent, which consist of pressure, mass, and energy variation equations. The results are derived in the form of contours and graphical representations of variations in bed temperature and hydrogen concentration. It is observed that the system produces 40 kJ of upgraded heat with heating capacity of 0.1 kW and COP of 0.46 at 880 seconds of hydrogen transfer time for 250 g of each alloys.