Development and Performance Testing of a New Ceramic Recuperator

Metal heat exchangers have been used in industrial heat recovery applications for many years. Ceramic heat exchangers are relatively new, but are gaining acceptance as more field experience becomes available. The advantage of the ceramic units over metal units is the higher temperature capabilities of the ceramic which eliminate the need for costly over-temperature controls and dilution air systems. The problems encountered with ceramic heat exchangers to date have been variable leakage and lack of durability. These problems are associated with the high thermal stresses in the compact designs and with the seals required to connect the ceramic to the metal ductwork. Coors Porcelain Company has been engaged in the development of ceramic heat exchangers for heat engine and industrial applications for several years. Durability problems were encountered from thermal stresses in these applications with recuperators made from conventional ceramics. This resulted in development' of a new ceramic mixed oxide material specifically for heat exchangers. Changes in geometry of the ceramic matrices were also made to further reduce the stresses in order to increase product durability. A housing was designed and a ceramic gasket was selected to minimize the chances of significant leakage from the seal area of the recuperator. The performance of different recuperator designs and the durability results attained to date will be presented as well as results on field testing