Preliminary Design and Projected Performance for Intercooled-Recuperated Microturbine Available to Purchase

The Inter-Cooled-Recuperated (ICR) cycle is recognized for its high efficiency potential in gas-turbine applications. This paper reports on a proposed implementation of the ICR cycle in a microturbine setting, using a three-spool configuration incorporating a variable-geometry nozzle on the low-pressure ‘free’ power turbine. Hardware specified for the high-pressure turbine is an existing ceramic rotor fabricated and spin-tested in connection with a prior DOE-sponsored program. Rated engine design-point power and efficiency are projected at 378kWe and 39.5% (net LHV), under realistic prescriptions for component efficiencies and parasitic losses, and with TIT = 1366K (2000°F) specified for the ceramic rotor. Detailed off-design performance projections are carried out, demonstrating exceptional range and part-load efficiency. A key attraction of the ICR compared to a non-intercooled recuperated cycle is its compatibility with high cycle pressure ratio, making for dramatic size and cost reductions for high-pressure components, most importantly the recuperator. A related advantage is reduced ceramic-turbine rotor diameter for a given power level, extending the applicability of ceramic components under conservative manufacturability limits. Engine layout and preliminary mechanical designs for the major subassemblies are developed for application to a forty-foot transport bus with hybrid-electric drive. Further applications under evaluation for the proposed microturbine are stationary power generation, and in a hybrid powerplant setting using a solid-oxide fuel cell.