Experimental studies of organic Rankine cycle systems using scroll expanders with different suction volumes

By using R123 as the working fluid, experimental studies for basic organic Rankine cycle (BORC) and organic Rankine cycle with a regenerator (RORC) are carried out, two scroll expanders with different suction volumes are installed and examined (1# expander with the suction value of 66 mL/r; 2# expander with the suction value of 86 mL/r). Comparison between the different system configurations and expanders with different suction volumes are carried out under identical heat source conditions, how the expanders with the different suction volumes influence the system performance is investigated and analyzed. The torque of the expander is increased step by step during the experiment. The results show that: 2# expander shows a higher shaft power output as well as rotating speed, but lower isentropic efficiency in most situations; the highest shaft power output appears when the filling factor reaches to 0.8–0.9. For different system configurations, the maximum actual thermal efficiency of 2.96% is obtained in BORC using 2# expander. The heat transfer rate of the evaporator is decreased due to the regenerator, however, RORC still has a lower thermal efficiency due to its low shaft power output. The different mass flow rate caused by the different suction volume of the expander is the most important factor that influences the system performance.