Wilson TurboPower (WTPI) is developing a 300-kW microturbine that is designed to achieve 50% electrical efficiency. This is unusually high given the history of lower efficiencies demonstrated by small engines of any type, including diesels. However, WTPI has chosen a cycle capable of producing high efficiency as well as specifying components (compressor, heat exchanger, and turbine) that can operate at high efficiencies. The key enabling technology is the company's ceramic regenerator, based on MIT technology and licensed by WTPI. It is capable of handling high-temperatures (>1000°C) at high-effectiveness (97.5%) with a low pressure drop (e.g., 1 – 2 percent). The high effectiveness results thermodynamically in a requirement of a low cycle pressure ratio (about 2.5:1) for optimum performance. The component efficiencies of compressors and turbines of low pressure ratio are intrinsically high. WTPI also divides this low pressure ratio among four compressor stages and three turbine stages. Doing so greatly reduces the kinetic energy that is lost from single stages, and thus substantially improves the component efficiencies. The blade peripheral speeds are also low, leading to relatively very low stresses in the ceramic turbine and therefore to great confidence in its integrity. The ceramic regenerator makes possible higher operating temperatures, further increasing efficiency. By these means a shaft-power efficiency of 55% can be confidently predicted for the 300-kW engine, which when coupled to a high-efficiency electrical generator would lead to an electrical efficiency of about 50%.
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