Automotive Turbogenerator Design Considerations and Technology Evolution

For the gas turbine to find acceptance in the hybrid electric automotive market its major features must be dominated by the following considerations, low cost, high performance, low emissions, compact size and high reliability. Not meeting the first two criteria has been nemesis of earlier attempts to introduce the gas turbine for automotive service. With emphasis on the design simplicity for low cost and high performance, this paper addresses design considerations for the major components, and overall turbogenerator configuration. Initially all metallic engines will be introduced in hybrid electric vehicles, but their high cost will likely preclude them from the high volume commercial market. To match or better the performance and cost of advanced automotive piston engines, the success of the very small turbogenerator is viewed as being dependent upon the use of ceramic components in the hot-end, including the turbine, combustor, recuperator and ducts. The projected evolution from today's state-of-the-art all metallic engines, to advanced technology ceramic units for service in the first decade of the 21^st century, is a major theme in this paper.