High Speed Spinning Scroll Expander (HiSSSE) - Organic Rankine Cycle for Increased Naval Ship Power Density and Fuel Efficiency

Waste heat from Naval diesel generators provides significant opportunity to introduce organic Rankine cycles (ORC) to increase their fuel efficiency. The objective of the proposed effort is to design and demonstrate a high-speed, spinning scroll expander (HiSSSE) ORC as a power dense waste heat recovery system for diesel generators on ships. The system will leverage Air Squared’s spinning scroll technology to increase efficiency, reduce size and weight, and increase reliability with a low part count. Assuming 7% thermal efficiency of an ORC, a power output of 243 kW is possible. This expander leverages novel dynamics which allows the machine to run at higher speeds thus achieving more flow within a smaller footprint. This novel design offers the best of both dynamic and positive displacement expander solutions. As a positive displacement expander, it can achieve a high-power output with minimal reduction in flow. Due to the spinning motion, various centrifugal loads are eliminated from a traditional orbiting type design which allows the expander to operate at much higher speeds, thus reducing size and weight. Additionally, the spinning motion removes the need for a counterbalance common in orbiting scroll designs. This further reduces weight by eliminating counterweights and eases bearing loads.