超临界二氧化碳压缩测试系统动态模型

Dynamic model of supercritical carbon dioxide compression testingsystem

建立超临界二氧化碳(S-CO_(2))压缩测试系统的动态仿真模型对于系统设计、系统性能预测以及控制策略的建立具有重大意义。首先,考虑冷却器和管道的时滞效应,建立了冷却器、压缩机和节流阀等部件的热力学模型,并结合系统焓方程形成系统动态仿真模型,并验证了模型的静态与动态精确性。在此基础上,研究了某350 kW S-CO_(2)压缩测试系统对节流阀开度扰动的动态响应特性。结果显示:在节流阀开度增大过程中,压缩机进口温度几乎不变,压比降低,压缩机效率与输出功率先增大后减小,稳定后压缩机效率略有增大、输出功率几乎不变;在节流阀开度线性增大时,回路流量和压缩机进口温度存在最大调节量,二者均与节流阀开度变化率呈近似线性关系;在压缩机前增设300 L缓冲罐将使系统稳定时压缩机流量、压比和效率等参数出现偏移,但不影响压比和效率等参数在节流阀开度调节过程中的变化趋势,增强了压缩机对节流阀开度扰动的鲁棒性。

The establishment of system dynamic simulation model of supercritical carbondioxide(S-CO_(2))compression test system is of great significance to system design,system performance prediction and control strategy establishment.Consider time lag effect of the cooler and the pipe,a component-level thermodynamic model of the cooler,compressor and orifice plate is firstly established,and a dynamic simulation model is built upby combining the enthalpy equation of the system.The staticand dynamic accuracy of the model is validated.On this basis,the dynamic response characteristics of a 350kW S-CO_(2) compression test system to the orifice plate opening disturbance are studied.The results show that,during the increase process ofthe orifice opening,the inlet temperature of the compressor almost unchanges,the pressure ratio decreases,the efficiency and output power of the compressor increasesat first and then decreases.When the orifice opening is constant,the compressor efficiency increases slightly and the output power almost has no change.When the orifice opening increases linearly,the loop flow rate and compressor inlet temperature have the maximum adjustment,and both of them have a linear relationship with the opening change rate.Besides,adding 300L tank in front of the compressor will offset the system stability parameters and enhance the compressor’s robustness to the throttle valve opening disturbance.