A comprehensive approach for alloy selection in metal hydride thermal systems

• Developed open-source hydride analysis toolbox with accompanying alloy database.
• Evaluated performance of 3999 hydride pairs in a heat pump system.
• Investigated hydride performance statistics by hydride type.
• Compared static and dynamic system coefficient of performance (COP).

Metal hydride thermal systems can be used in a variety of applications, but the selection of hydrides for such systems is often limited to a narrow set of materials. In this work, we present the methods and accompanying property database to conduct a comprehensive material selection analysis for a metal hydride thermal system using a database of over 300 hydrides from the open literature. To use this data effectively, we developed a robust thermodynamic equilibrium model that can be applied to a wide range of hydride types, a set of generic reaction rate expressions, and a set of relevant thermophysical property models. The combination of these features—distributed as a freely available object-oriented MATLAB® Toolbox—allows consideration of over 100,000 possible hydride pairs for a given two-hydride thermal system and shows trends otherwise unavailable from an analysis of only a few hydride pairs. We use a metal hydride heat pump system to demonstrate this capability and to identify trends of system coefficient of performance (COP) and the fraction of hydrogen transferred between hydrides. Using the simulation results from the 3999 hydride pairs which have suitable thermodynamics to work in the metal hydride heat pump system, we show that the system COP calculated only from material parameters is not a reliable predictor of the dynamic system COP.