A phase change material (PCM) heat exchanger device comprising heat exchanger cells (1a, 1b) operating on the regenerative countercurrent principle, one or more phase change material (PCM) accumulators (2, 3) provided in the heat exchanger cells and one or more vortex tubes (6, 7, 8). When the directions of the air, gas and liquid flows are cyclically reversed in the apparatus, energy is recovered into the heat exchanger cell and the PCM accumulator, and during the subsequent cycle, the energy is released from the heat exchanger cell and PCM accumulator. While one heat exchanger cell and PCM accumulator is being charged, the other heat exchanger cell and PCM accumulator is simultaneously discharged. Warm air exits a first outlet port while cold air exits a second outlet port of the one or more vortex tubes. The fluid flows heat or cool the heat exchanger cells and associated PCM accumulators.