Compact Turbo-Rankine Bottoming Cycle

Electric generators for military and civilian applications produce large amounts of waste heat. This heat can produce additional electric power via a bottoming cycle. The resulting power would enable the use of more electronic devices and/or reduce fuel consumption and its associated costs and logistical burdens. Large power plants frequently use bottoming cycles, but smaller generators rarely include them. The primary reason is that the bottoming systems would be relatively large and inefficient for the low heat source temperatures and low power capacities associated with mobile generators. Fundamental thermodynamic limits, scaling penalties, and manufacturing constraints are the greatest obstacles. To accommodate these limitations, Creare has focused intense effort on the development of miniature turbomachines, advanced heat exchangers, and small thermodynamic systems for nearly 30 years. For this project, we are developing a turbo-Rankine system that can be used as either a bottoming cycle or a standalone generator. The resulting system will have very high power density and efficiency. During Phase I, we performed design analyses, conducted trade studies, developed preliminary designs for the components and system, and assessed producibility and life-cycle costs. During Phase II, we will fabricate our turbo-Rankine generator and demonstrate its performance.