Phase-change energy storage unit and ternary unidirectional/bidirectional phase-change energy storage system

The utility model provides a phase-change energy storage unit and a ternary unidirectional/bidirectional phase-change energy storage system. The phase-change energy storage device comprises a shell, a phase-change energy storage body, a refrigerant pipe, a waterflow channel and a control device, wherein a waterflow inlet, a waterflow outlet, a refrigerant inlet and the refrigerant outlet are arranged on the shell; the phase-change energy storage body, the refrigerant pipe and the waterflow channel are arranged in the shell; and the phase-change energy storage body comprises a phase change material and a metal container which is used for containing the phase change material. The phase-change energy storage unit and the ternary unidirectional/bidirectional phase-change energy storage system are efficient in heat transmission, safe, reliable, energy-saving and environment-friendly.