For the problem of periodic heat release in the practical application of phase-change thermal storage materials

a response surface method was used to design an experimental program on an indirect heat accumulator

based on a circular erythritol/expanded graphite composite phase-change material. The performance evaluation of the thermal storage unit was carried out through the total heat release

potential heat

and effective energy utilization of the thermal storage material. The results showed that when the intermittent time was 20 min and the cumulative heat release time of the material was 40 min

with the increase in running time

the total heat release

Stephen number

and exergy efficiency had extremum values. In addition

the appearance time of the extremum of the exergy efficiency was 22% lagged behind those of the total heat release and Stephen number. It was concluded that the running time of 7.7 min is the best value that simultaneously satisfies the optimization of the three evaluation indicators.