Abstract: Heat is exchanged between high and low temperature gases in a regenerator type of heat exchanger, wherein the high temperature gas is conducted through a high temperature passage formed in a housing, and the low temperature gas is conducted through a low temperature passage formed in the housing. A porous heat transfer core is rotated such that portions of the core pass sequentially through the high and low temperature passages. The high temperature gas traveling in the high temperature passage is caused to flow through, and heat, a portion of the core disposed in the high temperature passage. The low temperature gas traveling in the low temperature passage is caused to flow through, and be heated by, a heated portion of the core disposed in the low temperature passage. A low pressure zone is established in a chamber situated at each location where the core travels from one of the passages to the other.