An extensive parametric analysis on the performance of a single-stage metal hydride heat transformer

The metal hydride heat transformer shows great potential for the low-grade heat recovery. However, the heat output is variable, and these dynamics have to be taken into account in realistic applications. In this paper, a new index called true temperature boost is introduced together with conventional indices to assess the performance of the heat transformer system. Detailed analyses are carried out using a mathematical model that authors developed, investigating effects of key design and operating factors on the system’s performance. The amount of hydrogen transferred between coupled reactors is found to be crucial to obtain a high coefficient of performance, while specific heating power is very sensitive to the cycle time. On the true temperature boost, the driving force of reaction and the heat transfer conditions exert the most significant effects.

► A new dynamic index was defined for metal hydride heat transformer.
► Design and operating factors for discussion were clarified.
► Detailed parametric analysis was conducted by numerical simulation.
► Specific heating power was found quite sensitive to the cycle time.
► The new index was found to mainly depend on reaction driving force.