Conception and First Functional Tests of a Novel Piston-Type Steam Expansion Engine for the Use in Stationary WHR Systems
For the recovery of unused process heat of various origins, the use of Rankine-Cycles represents an effective and well-proven strategy. As most commercially available systems are designed for comparably high power, or, if scaled down, are suffering from low efficiency or high costs, the present research project aims at designing a novel steam expansion engine for medium power (for waste heat power around 300 kW).
The so-called rotational wing-piston expander uses two pivoting shafts, each holding two wing-like pistons, within one housing, that are performing a cyclic movement relative to one another. This way, four working chambers with varying volumes are resulting, each experiencing repetitive compression and expansion. The conversion of the cyclic changing angular velocity to a constant rotation at the output shaft is done via a non-circular gear. This solution offers the possibility of sealing the lubricated gearbox against the steam-flooded section containing the working chambers via rotational seals, which is much easier than the sealing within a conventional reciprocating piston engine. The sealing of the working chambers themselves, however, poses a challenging task. Therefore, various sealing solutions have been developed and, via basic principle tests, investigated. The most promising solutions have been chosen for the use in a scaled test version of the expander, for the investigation at the steam test bench at IVT at TU Graz.
The paper shows the development and the operating principle of the expander, as well as the main challenges, focusing specifically on the sealing; additionally, first test results are presented.
KeywordsSteam expansion engine Rotational wing piston Sealing
- 1.Horn, H.: Beitrag zur Beurteilung berührungsfreier Kolbendichtungen (Labyrinthkolben) im Luftverdichter. Diss. TU Dresden: VDI-Z (1965)Google Scholar
- 2.Prof. Dr.-Ing. habil. Haas, W.: Lehrgang Dichtungstechnik. http://www.ima.uni-stuttgart.de/pdf/dichtungstechnik/skript_dichtungstechnik.pdf (2018)
- 3.ZHAW Homepage: https://www.zhaw.ch/storage/engineering/institute-zentren/iefe/PDFs/orc-fachartikel-et036-aus-abwaerme-wird-strom.pdf. Accessed 18 Sept 2018
- 4.Burckhardt Compression Homepage. https://www.burckhardtcompression.com. Accessed 18 Sept 2018
- 5.GFD Homepage. http://www.seals.de/. last accessed 24 Sept 2018