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

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