TESTING AND MODELING A VANE EXPANDER USED IN AN ORC WORKING WITH HEXAMETHYLDISILOXANE (MM)

asme-orc2015 Tracking Number 136

Waste heat from industrial production carries considerable potential for further use. Organic Rankine Cycle (ORC) brings a possibility to produce electrical energy from heat, originally intended to release to the surroundings. For ORC with power output up to 10 kW, small-scale turbines are still expensive to manufacture and their use can be problematic in terms of high shaft speed or quality of inlet steam. It is therefore preferable to use positive displacement expanders. The first part of this paper presents and analyses the measurements conducted on a prototype of vane expander. This vane expander characterized by a 1 kW power output operates in an ORC that uses hexamethyldisiloxane as a working fluid. The expander inlet temperature varies approximately from 135 °C to 150 °C, inlet pressure varies approximately from 200 to 300 kPa abs, isentropic efficiency from 0,4 to 0,58. The second part of the paper proposes a grey-box model, which is calibrated on the base of the measured data. This lumped-parameter model takes into consideration major losses of the expander: supply and discharge pressure losses, under and over-expansion, internal leakages and mechanical losses. The model is finally used to assess the impact of each source of losses on the overall performance of the expander.