Absorption power cycle with a 3D-printed plastic micro turboexpander - Considerations, design and first experimental results

Absorption power cycle (APC) using water-lithium bromide (LiBr) as a working fluid is a novel concept especially suitable for micro scale low temperature distributed power systems. Theoretical investigations provide various benefits in comparison to alternatives such as organic Rankine cycles, but technical design poses many challenges as well. Regardless of similarities with LiBr absorption chillers, no LiBr APC has been to authors’ knowledge experimentally operated. This paper focuses on an experimental development of a proof-of-concept APC operating with LiBr solution. The first part contains an introduction of the experimental system built, the first tests and experimental results of the cycle. The main part of this work focuses specifically on the expander design and performance. After discussing turbine considerations, axial steam micro turboexpander with plastic 3D printed components (rotor and stator) with design power output of approx. 300 W is described. Experimental performance is presented and compared to the design point.