Design And Analysis Of A Miniature Rotary Wankel Compressor


Design and analysis of a meso-scale rotary Wankel compressor is presented here. The compressor is primarily designed for a hand-held power generation system, based on a modified Brayton cycle and capable of producing 20 W with a specific energy of 2400 to 3800 W-hr/kg for usage duration of 72 to 240 hours. The small size of the overall system makes the conventional design, rules and concepts inappropriate, thus requiring new design concepts for the compressor and other components. In the current design, the major axis of the epitrochoid is 14 mm. The three-lobed rotor is driven by a drive shaft through an internal gear system such that each revolution of the rotor corresponds to 3 revolutions of the drive shaft and 6 compression "strokes". There are two intake ports and two discharge ports. The valves within these ports operate to limit the pressure ratio to 2.5, the target of the design. Rotor thickness is 9.1 mm and at a rotational speed of 5000 rpm, the compressor can provide a flow rate of 0.138 g/s air, as needed by the power generation system. The pressure ratio of the compressor is a function of geometry (not rotor speed), and hence this design is well-suited for load following in a variable load application. Its drive shaft can be de-coupled from other system components of the power generation system. This mechanical isolation can lead to thermal isolation, which is essential for miniature power generation devices. Micro-stereo lithography and micro-EDM appear to be the best methods to fabricate the necessary components of the compressor. Micro-stereo lithography, in particular, can provide a seamlessly integrated compressor, thus reducing the integration and assembly cost Micro-EDM is more suited for production of large batch sizes because of the relatively high initial cost More sophisticated micro-fabrication methods such as LIGA, UV-LIGA and lithography SU-8 can also be used. However, since the device thickness is rather large compared to what is typically done with these methods, multiple layers need to be bonded in both of these approaches because of the large thickness of the proposed design.

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ASME International Mechanical Engineering Congress and Exposition, Proceedings



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Article; Proceedings Paper

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1542620772 (Scopus)

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