The Organic Rankine Cycle (ORC) driven by low-grade energy can operate in off-grid mode. Here, we report the steady and transient characteristics of an ORC system. A single screw expander and a synchronous generator convert mechanical power to electricity. A lamp array simulates the variable external loads. The quality parameters including electric frequency, electric power and effective voltage are measured by a power meter. We show that at setting frequency of 50 Hz, the maximum system efficiency can be reached when the external load is not larger than the ORC power capacity. The expander isentropic efficiency is above 80% for the vapor superheating of 5–10 K at expander inlet. A control strategy is proposed to achieve better system performance under varied heat source and environment conditions. By use of residual frequency and adjusting pumping frequency, the vapor pressure at expander inlet can be automatically adjusted to reach the optimal value. Transient tests indicate that the electric quality is insensitive to the step change of external loads and heat/cold sources parameters. The thermohydraulic parameters are self-adapted to the change of external parameters. This work provides a self-adapting strategy for ORC operation at varied heat/cold source parameters.

中文翻译：

---

有机朗肯循环电力系统的稳态和瞬态运行

由低品位能源驱动的有机朗肯循环 (ORC) 可以在离网模式下运行。在这里，我们报告了 ORC 系统的稳态和瞬态特性。单螺杆膨胀机和同步发电机将机械能转化为电能。灯阵列模拟可变的外部负载。电频率、电功率、有效电压等质量参数由功率计测量。我们表明，在设置频率为 50 Hz 时，当外部负载不大于 ORC 电源容量时，可以达到最大系统效率。膨胀机入口蒸汽过热度为 5-10 K 时，膨胀机等熵效率在 80% 以上。提出了一种控制策略，以在不同的热源和环境条件下实现更好的系统性能。通过利用残余频率和调节抽吸频率，可以自动调节膨胀机入口蒸汽压达到最佳值。瞬态测试表明，电能质量对外部负载和热/冷源参数的阶跃变化不敏感。热工水力参数自适应外部参数的变化。这项工作为在不同热/冷源参数下的 ORC 操作提供了一种自适应策略。