Reversible latent heat storage method, and reversible latent heat accumulator

A system for utilizing latent heat stored in a crystallizable liquid heat storage medium subject to super-cooling, wherein the storage medium is continuously circulated past a heat exchanger positioned in the upper portion of an enclosed space containing a body of such storage medium to effect super-cooling thereof, then past a bed of seed crystals in the lower portion of such space to effect partial crystallization thereof, and then back past the heat exchanger.