Abstract: In this paper, a concentric trocar phase change heat storage unit filled with palmitate acid was studied. The thermal storage performance test system was established and the phase change heat transfer process was simulated by numerical simulation. By comparing the experimental results with the simulation results, the accuracy of the numerical calculation method was verified. The enhanced heat transfer characteristics of helical rib structure on heat storage unit and the influence of dimensionless pitch and dimensionless rib height on melting process were studied. The results show that under the combined action mechanism of heat conduction and local natural convection of phase change material（PCM）, the heating charge time is significantly shortened, and the melting rate increases first and then decreases. Reducing the pitch and increasing the rib height can shorten the charging time, but reduce the heat storage. Based on the analysis of charging time, heat storage and average heat flux, the parameter combinations of dimensionless pitch and rib height are 0.24 and 0.59 by single factor optimization. Under the structure, the heating duration was 240 min, and the average heat flux was 1056 W/m~2.