Method for producing a heat regenerating material particle

A method for producing a heat regenerating material particle comprising:

• preparing a slurry by adding a powder of a heat regenerating substance to an alginic acid aqueous solution and mixing the powder of the heat regenerating substance and the aqueous alginic acid solution;
• and
• forming a particle by gelling the slurry by dropping the slurry into a gelling solution, the gelling solution containing one metal element selected from the group consisting of calcium (Ca), manganese (Mn), magnesium (Mg), beryllium (Be), strontium (Sr), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), and cobalt (Co),
• wherein, in the forming of the particle, a gelation time is controlled so that a concentration of the metal element in a first region of the particle becomes lower than a concentration of the metal element in a second region,
• wherein the second region is closer to an outer edge of the particle compared to the first region,
• wherein the first region and the second region comprise the heat regenerating substance, and
• wherein the heat regenerating substance comprises an oxide or an oxysulfide.