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A rotary ceramic regenerator is the most efficient high temperature heat exchanger being considered for the automotive gas turbine application. Under the HVTE-TS program sponsored by the U.S. Department of Energy, our activities have focused on the identification and development of materials and on the development of hardware required for the extrusion of this product. Initially, five ceramic materials were identified which showed promise for meeting the performance criteria of the product. Of these five, lithium-aluminosilicate (LAS) glass and magnesium-aluminosilicate (MAS) ceramic batches were chosen. MAS materials had been developed for use in automotive catalyst supports and so have cost and processing advantages for automotive applications. Cellular MAS parts have been extruded, fired, finished, and supplied to Allison Engine Company for testing. LAS products have been in use for many years in gas turbine regenerators throughout the world.

In the preceding paper the specific heat capacity, substrate heat capacity, and energy requirements of two types of substrates were discussed in detail both from the standpoint of predictions from measured material property values as well as actual energy measurements on ceramic and metal products. This information is valuable for the catalyst designer because of the light-off impact of this energy requirement. Some material was also presented regarding the change in this energy requirement with washcoat loading. Other aspects of the substrate which could reasonably come into play to enhance the light-off characteristics of a catalyst are the rates of heat and mass transfer. The latter of these could reasonably be expected to drive the catalyst activity. In addition, the pressure drop which results from the substrate structure could influence and limit the choice of cell configurations and product shapes and sizes, thereby constraining the list of possible options.