Triple pass ceramic cross-flow heat recuperator

A heat recuperator comprising a cross flow ceramic core within a housing, the core comprising ribbed layers for the flow therethrough of combustion air to be heated, the core also comprising other ribbed layers for the flow therethrough of hot exhaust gas, the combustion air ribbed layers being stacked alternatively with the hot gas ribbed layers, the air flow through the combustion air ribbed layers being orthogonal to the gas flow through the hot gas ribbed layers, the air flow through the combustion air ribbed layers being triple pass, the passes being separated from each other by divider ribs, each pass having supporting ribs therein providing channels for the air flow, the construction of the divider ribs being such as to reduce the number of said supporting ribs required for support of all the layers in the core, the divider ribs being thicker than the ribs in the hot gas ribbed layers, the divider ribs being sealed to prevent air in one pass from leaking to an adjoining pass, and metal inserts in the housing that face with the divider ribs so as to cause the air flow to be triple pass.