Analysis of crossed vanʹt Hoff metal hydride based heat pump

In this paper, the operating feasibility of a single-stage metal based hydride heat pump (SS-MHHP) working on the principle of crossed vanʹt Hoff line concept is presented. The performance of the system is predicted by solving the unsteady, two-dimensional mathematical model in an annular cylindrical configuration employing two different hydride alloy pairs, namely, V0.846Ti0.104Fe0.05/Fe0.9Mn0.1Ti and V0.855Ti0.095Fe0.05/MmNi4.7Al0.3 (regeneration alloy/refrigeration alloy). The influences of heat source (TH) and refrigeration (TC) temperatures on the amount of hydrogen transferred between the paired reactors, coefficient of performance (COP) and specific cooling power (SCP) of the crossed vanʹt Hoff SS-MHHP system are studied. Within the selected ranges of operating temperatures, the COP of the crossed vanʹt Hoff SS-MHHP is about 60% higher than the conventional single-stage MHHP. The optimum operating temperatures of V0.846Ti0.104Fe0.05/Fe0.9Mn0.1Ti and V0.855Ti0.095Fe0.05/MmNi4.7Al0.3 combinations are found to be 373/303/291 K and 400/303/283 K (heat source/heat sink/refrigeration temperatures), respectively. At the optimum operating temperatures, the COP and SCP of the V0.846Ti0.104Fe0.05/Fe0.9Mn0.1Ti and V0.855Ti0.095Fe0.05/MmNi4.7Al0.3 combinations are 0.89 and 30.8 W/kg of total mass and 0.86 and 30.3 W/kg of total mass, respectively.