Conceptual Engine Design Study for a 400kWe ICR Turbogenerator

Abstract

The thermodynamic performance and relative sizing of an intercooled recuperative (ICR) cycle turbine engine, for a 400 kWe turbogenerator with a thermal efficiency goal of 40% was studied. The study encompassed four candidate ICR engine flowpath configurations comprising of single shaft and two spools designs with the various methods of power output extraction. The study confirmed that the basic attributes of the ICR cycle are higher specific power, kWe/kgs inlet flow, and a high thermal efficiency characteristic. The major challenge to attaining a turbogenerator thermal efficiency of 40% is inexorably linked with the ability to operate at turbine inlet temperatures of the order 1100C, together with high compressor and turbine efficiencies. This is perceived attainable without internal blade cooling, or ceramic materials by adopting an externally cooled high tip speed radial turbine to drive the high pressure spool of a conceptually simplified ICR turbogenerator. The conceptual engine flowpath would comprise two separate non-concentric spools, wherein the low pressure “supercharging” spool might feasibly be an existing variable turbine nozzle turbocharger.