Design Considerations and Experimental Results of a 60 W Compressed-Air-to-Electric-Power System

In many process applications, where a pressure reduction is required the energy ends up being dissipated as heat. Examples are throttling valves of gas pipelines and automotive engines or turbo expanders as used in cryogenic plants. With a new pressure reduction system that produces electricity while expanding the gas, this lost energy can be recovered. To achieve a high power density this energy generation system requires an increased operating speed of the electrical machine and the turbomachinery. This paper proposes a miniature compressed-air-to-electric-power system, based on a single-stage axial impulse turbine with a rated rotational speed of 350000 rpm and a rated electric power output of 60 W. A comprehensive description including turbine and permanent magnet (PM) generator is given and measurements like maximum electric output power of 124 W and maximum system efficiency of 24% are presented.