Conception and First Functional Tests of a Novel Piston-Type Steam Expansion Engine for the Use in Stationary WHR Systems

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


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.
Original languageEnglish
Title of host publicationEnergy and Thermal Management, Air-Conditioning, and Waste Heat Utilization
Subtitle of host publication2nd ETA Conference, November 22-23, 2018, Berlin, Germany
PublisherSpringer Nature
Number of pages17
ISBN (Electronic)ISBN 978-3-030-00819-2
ISBN (Print)ISBN 978-3-030-00818-5
Publication statusPublished - 23 Nov 2018

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