Cost competitive 30 kW gas turbine/generator demonstration for cogeneration or solar-electric applications

The author demonstrates the performance of a Brayton-cycle gas turbine engine. The Brayton cycle studied is a highly recuperated, low-pressure-ratio, two-shaft open cycle. The novelty in this approach is that the turbine engine was composed of stock turbocharger components. Internal combustion occurs between the compressor and turbine of the gasifier section. The surplus energy exhausted from the gasifier drives the power turbine, which is directly coupled to a gearbox that drives the standard 60 Hz induction generator. Using two turbines to separate the work of the compressor from that delivered to the generator allows for a relatively low-speed power turbine and thus a long-lived single-stage gearbox. The testing, completed in October 1988, utilized an unrecuperated test rig to demonstrate the two-shaft turbogenerator configuration. At a power level of 33 kWe (60 Hz, 480 V), the test data implied that with a 94% recuperator, a thermal-to-electric efficiency of 32% was attained.<>