Paper No 239 – Lubrication management of a reversible compressor expander unit in a combined HP ORC plant
Combining a heat pump cycle with an Organic Rankine cycle and adding a thermal storage enables an innovative and reversible energy storage concept. As both processes use similar components, it is conceivableto combine these in one single cycle with two operation modes.Within an ongoing research project at University Erlangen-Nuremberg, a combined HP-ORC pilot plant is designed and constructed. One focus in the research is the combination of the compressor of the heat pump and the expander of the ORC in one single machine (e.g. screw-type). Besides the pressure ratios and temperature levels, the lubrication is an interesting challenge, as it differs in quantity and function. Several innovative designs of the lubrication system are conceivable. The oil separator is an essential component of the lubrication circuit. With methods of CFD-simulation, a close look at the separation in both operation modes (HP and ORC) is possible. This paper describes preliminary considerations, shows design methods and identifies solutions for the lubrication management of a reversible compressor-expander unit