Thermodynamic Analyses Of Organic Rankine Cycle With Ejector

The low power capacity and 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 and its efficiency an Organic Rankine Cycle with Ejector (EORC) and dual-expander Organic Rankine Cycle (DORC) were proposed in this paper. EORC included the EORC by vapor ejector (VEORC) and the EORC by liquid ejector (LEORC).The expander’s outlet pressure was decreased in EORC compared to the ORC, so the power capacity was increased due to the use of ejector. The thermodynamic analyses about those four power cycles were carried out in the paper.To achieve the maximum net output power and high system efficiency, the thermodynamic analyses of ORC and VEORC by the heat source between 60 and 100℃were conducted. Four representation working fluids chosen as the suitable working fluids in ORC and VEORC were R227ea, R245fa, R134a and R123. The research about the mixtures used in the ORC and VEORC were carried out, which showed that N1/N4 by 50% /50% as the mixture working fluid could gain more net output power and higher system efficiency than R227ea.It was considered that the entrainment ratio of ejector affected the cycle performance of EORC. When the net output power was the largest, the entrainment ratio was up to 1.9 in VEORC. While the entrainment ratio was 0.3, the performance of LEORC was better.The investigation on the performance of these four cycles was conducted at the aim of the maximum net output power by the heat source between 60 and 100℃. At the heat source of 95℃, the cycle performance of net output power and efficiency was calculated and analyzed in those four cycles. It is shown that the cycle performance of LEORC was better than that of the other three cycles.The experimental study on the ORC and VEORC were conducted. It was demonstrated that the more output power and higher work efficiency were produced in the VEORC than that in the ORC, which reflected the advantages of cycle performance in the EORC.