A novel three-dimensional cross-arranged fin structure for performance enhancement of thermochemical heat storage

Abstract

Thermochemical heat storage technology stores and releases heat through reversible reaction, which has the advantages of large heat storage density and long heat storage period. However, the poor heat transfer in reactor weakens the heat storage performance. In present paper, a novel three-dimensional cross-arranged fin structure is proposed to enhance the heat transfer process in a shell and tube reactor with Mg(OH)2 as thermochemical material. The comparative studies are performed for the three reactors with the novel fin, traditional axial fin under the same metal amount and without fin, respectively. It is found that the novel cross-arranged fin enhances heat transfer more efficiently and uniformly, thus it reduces heat storage time significantly. The charging time is reduced by 67.3 % and 25.3 % respectively, compared with no fin and axial fin reactors. After that, the effects of bed thermal conductivities, operating conditions and geometry parameters on heat storage performance of the novel fin reactor are analyzed to further verify the advantages of the new fin under wide working conditions. Moreover, the hydration process is also discussed. The cross-arranged fin reduces the discharging time by 18.9 % compared to the axial-fin reactor. In short, installing the cross-arranged fin is an effective way to improve the thermochemical heat storage performance due to its excellent heat transfer enhancement effect, and it is worth considering for the design and optimization of thermochemical heat storage reactor.