Stirling Engines for Hybrid Electric Vehicle Applications

Stirling engines are excellent candidates for the power conversion system in hybrid electric vehicles due to their low emissions levels and high conversion efficiency. Laboratory and vehicle chassis dynamometer test data using natural gas fuel are presented for kinematic Stirling engine emissions levels over a range of air/fuel ratios and exhaust gas recirculation (EGR) levels. Projections are made for emissions levels during a simple, assumed dual operating point driving cycle for which a battery supplies energy during periods of high demand and stores energy during periods of regenerative braking. The projected emissions levels are compliant with the 1995 California Air Resources Board (CARB) Mobile Source Emission Standards for ultra-low-emissions vehicles.