Multi-stage variable type waste heat storage and recovery apparatus and method thereof

A multi-stage variable type waste heat storage and recovery apparatus and method thereof are disclosed. The apparatus includes a phase change material storage unit for separating and arranging a plurality of phase change materials having different melting points, and arranging them in stages on a path of the waste heat so that a phase change material having a higher melting point is located closer to an inlet side of the waste heat; a use place registration unit; a temperature range storage unit; a phase change material selection unit for selecting a phase change material of a corresponding melting point; and a heat energy supply unit for supplying heat energy by the latent heat of the phase change material selected by the phase change material selection unit to a corresponding heat energy use place among a plurality of heat energy use places.