Effect of heat source supplies on system behaviors of ORCs with different capacities: An experimental comparison between the 3 kW and 10 kW unit

Organic Rankine cycle (ORC) is one of promising technologies for reducing energy consumption and carbon emission. In this work, the experiments of ORC systems with rated power capacities of 3 kW and 10 kW under the heat source of 150 °C were conducted, respectively. According to the theoretic analysis and experiment measurements, the ORC system performs differently with various heat sources. The heat source and heat sink primarily affect the pump and expander behaviors and then contribute to the overall performance. For the heat sources with the temperature of 81.5 °C–118.3 °C and 68.6 °C–123.5 °C, the overall system efficiencies of the 3 kW ORC and 10 kW ORC vary within the ranges of 2.67%–3.91% and 0.61%–4.59%, respectively. The optimal efficiencies of the systems are 3.91% and 4.59%, and the best outputs are 2.1 kW and 6.3 kW, with the corresponding supplied thermal power of 42 kW and 113 kW, respectively. The results indicate that, considering the similar structure and the same environmental conditions, the larger system has better performance when the heating supply is sufficient, and the coordination between system capacity, heat source, and heat sink is highlighted. The findings provide theoretical and experimental guidelines for the capacity arrangement of the ORC industrial design.