doi: 10.3850/978-981-08-7614-2_IMPRES046

ABSTRACT

This paper presents a feasibility study of a single-stage metal hydride heat pump (SS-MHHP) working on the crossed van’t Hoff line concept. The consequence of crossed van’t Hoff line SS-MHHP is to utilize the enthalpy of formation of the refrigeration alloy for driving the system. The performance of this system is predicted by solving the unsteady, two-dimensional, mathematical model in an annular cylindrical configuration using the finite volume method. Two different hydride alloy pairs are employed, namely, V_0.846Ti_0.104Fe_0.05 / Fe_0.9Mn_0.1Ti and V_0.855Ti_0.095Fe_0.05 / MmNi_4.7Al_0.3 (regeneration alloy / refrigeration alloy). The influences of heat source (TD) and refrigeration (TC) temperatures on the amount of hydrogen transfer between paired reactors, coefficient of performance (COP) and specific cooling power (SCP) of the system are studied. For the selected range of operating temperatures, the performance of the crossed van’t Hoff line SSMHHP is compared with the conventional SS-MHHP; a maximum improvement in COP of about 60% is found. For the selected hydride pairs V_0.846Ti_0.104Fe_0.05 / Fe_0.9Mn_0.1Ti and V_0.855Ti_0.095Fe_0.05 / MmNi_4.7Al_0.3, the optimum operating temperatures are found to be 373/303/291 K (heat source/heat sink/refrigeration temperatures) and 400/303/283 K, respectively. At the optimum operating temperatures, the COP and SCP are found to be 0.89 and 30.8 W/kg total system (including reactor mass) mass, for the V_0.846Ti_0.104Fe_0.05 / Fe_0.9Mn_0.1Ti hydride pair, while for the V_0.855Ti_0.095Fe_0.05 / MmNi_4.7Al_0.3 hydride pair the COP and SCP are 0.86 and 30.3 W/kg total system mass.

Keywords: Metal hydride, heat pump, crossed van’t Hoff line concept, thermal modeling.

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