Experimental study on the performance of the organic rankine cycles with and without internal heat regeneration

In this work, an organic Rankine cycle (ORC) with internal heat regeneration (referring to regenerative ORC) is designed and built, which uses refrigerant R123 as working fluid. Based on this experimental system, we test the performances of the ORCs with and without internal heat regeneration at different operating conditions. The result shows that when the heat source temperature is 100°C, the cycle efficiency are, respectively, 5.98% and 4.71% for the RORC and ORC although the output powers of both cycles are nearly the same which is about 510 W. The influences of four key parameters including the refrigerant charge, refrigerant flow, evaporating temperature and condensing temperature on the cycle performance are experimentally explored. It is indicated that there exists an optimal refrigerant charge of about 14.19 kg to result in the maximum output power. In addition, it is found that under the high torque, increasing the working fluid flow rate leads to the increase in the cycle performance. Under the low torque, however, lowering the flow rate can result in the increase in the cycle performance. Further, it is shown that the output performance of the system is increased with increasing the evaporating temperature. However, it is noticed that as the evaporating temperature rises, the influence of evaporating temperature on the output power fades out. Condensing temperature has no significant effect on the stability of the system.