Thermodynamic analysis of Organic Rankine Cycle with Ejector

The low efficiency of Organic Rankine Cycle (ORC) with low-grade heat source (LGHS) has limited its use in industry. In order to increase the power output capacity and its efficiency, an Organic Rankine Cycle with Ejector (EORC) was proposed in this paper. In the EORC, an ejector and a second-stage evaporator were added to the ORC. The vapor from the second-stage evaporator worked as the primary fluid for the ejector, to suck the exhaust from the expander so as to decrease the expander backpressure and increase the pressure difference through the expander, which resulted in an increase of the power output capacity. A Double Organic Rankine Cycle (DORC) was also introduced in order to analyze and compare the EORC with the ORC and DORC in the thermal performance. The output capacity was increased by EORC and DORC compared to the ORC. The thermal performance of DORC was superior to EORC, but another expander-generator and its auxiliary equipments were required for the DORC led to increase the investment and operation management compared to the EORC.

► An Organic Rankine Cycle with Ejector (EORC) based on the Organic Rankine Cycle (ORC) was proposed.
► A Double Organic Rankine Cycle (DORC) was introduced.
► An output efficiency of cycle was defined except the system efficiency.