Abstract:

In order to improve the stability of the system operation of the high temperature heat pump steam system with R1233zd(E) as the refrigerant under off-design conditions, a simulation model of the system was established based on Modelica to investigate the effect of the factors, such as with or without internal heat-exchanger (IHX), and heat source temperature, mass flow rate, and refrigerant mass flow rate on the system performance. The results showed that the coefficient of performance (COP) of the system improved by 16.1% after adding the IHX, the performance parameters tended to be more stable along the flow direction of the refrigerant, the farther away from the fluctuating source, and the sensitivity of the state parameters was ranked as: refrigerant flow perturbation>heat source temperature perturbation>heat source mass flow perturbation. In addition, the stability of all performance parameters under disturbances was improved by adjusting the throttle valve opening through a PI controller to improve the system's immunity to disturbances, especially the steam output under the refrigerant mass flow disturbance of the process was changed from unstable to more stable 140°C steam output, and the steam production under the three disturbance factors increased by 20.8%, 3.0% and 1.9%, respectively.

Key words: high temperature heat pump, flash steam, dynamic simulation, internal and external disturbances, optimization, Modelica

摘要：

为提升以R1233zd(E)为工质的高温热泵蒸汽系统在非设计工况下系统运行的稳定性，基于Modelica语言建立了系统的仿真模型，考察了是否带有回热器及热源温度、质量流量、工质质量流量这些内外扰动对系统性能的影响。结果表明，在添加回热器后系统的性能系数提升了16.1%，沿着工质的流动方向，越远离波动源工质性能参数越趋于稳定，且状态参数的灵敏性排序为：工质质量流量扰动>热源温度扰动>热源质量流量扰动。另外，为提高系统抗干扰性，通过PI控制器对节流阀开度进行调节，优化后内外部扰动下所有性能参数的稳定性都得以提升，尤其是工质质量流量扰动下从无法稳定输出蒸汽到以较稳定方式输出140℃蒸汽，且三扰动因素下其产汽量分别提升了20.8%、3.0%和1.9%。

关键词: 高温热泵, 闪蒸, 动态仿真, 内外部扰动, 优化, Modelica语言