The present invention relates to a heat exchanger which operates by blowing atomized or sprayed water against an evaporator pipe through which a refrigerant is circulating and by forcing air to circulate through the sprayed water, and to a refrigerating installation or a refrigerator in which the heat exchanger is used. This invention is useful for the refrigeration of cakes and perishable foods, for example, because a substance being refrigerated can be refrigerated while its moisture is prevented from evaporating, since the air cooled by the invention heat exchanger contains tiny water droplets and contacts the substance being refrigerated directly.