Abstract:

A rigorous dynamic mechanism model was established using Unisim for a complex heat exchange system (water cooled cascade refrigeration system) coupled with an ethylene propylene cascade refrigeration system and a circulating water cooling system in a certain device. Real time acquisition of on-site data was achieved using OPC technology, resulting in the establishment of an online dynamic simulation system. Through online dynamic simulation, synchronous tracking between the model and the on-site device was achieved. The online dynamic model can reflect the current operating status of the on-site device, thus obtaining a high-precision digital twin model. In addition, to address the issue of high system energy consumption, a global simulation optimization was conducted with the objective function of minimizing total system power consumption and the decision variable of circulating water temperature. Among them, for the calculation of fan power, a prediction model for fan power was obtained through regression using one year's historical data of the factory, thus solving the problem of power calculation in the optimization process. Finally, the optimization results were validated and calculated online in the digital twin model, and the optimization effect was predicted. After optimization, the system saved a total of 772.69MW in power consumption, with a total annual cost savings of 564000CNY, bringing significant economic benefits to the enterprise.

Key words: on-line dynamic simulation, cascade refrigeration, energy saving optimization, digital twin

摘要：

针对某装置的乙烯-丙烯复叠式制冷系统和循环水冷却系统耦合而成的复杂换热系统（水冷式复叠制冷系统），使用Unisim建立了严格的动态机理模型，并利用OPC技术实现了现场数据的实时获取，从而建立了在线动态模拟系统。通过在线动态模拟实现了模型与现场装置的同步跟随，在线动态模型可反映现场装置的当前运行状态，从而得到了一个高精度的数字孪生模型。此外，为解决系统能耗高的问题，以系统总功耗最小为目标函数，循环上水温度为决策变量，进行了全局模拟优化。其中，对于风机功率的计算，通过利用工厂一年的历史数据回归得到了风机功率的预测模型，从而解决了优化过程中功率计算的问题。最后，将优化结果在数字孪生模型进行了在线验证计算，并预测了优化效果。优化后系统总计节省功耗772.69MW，合计每年节省费用56.4万元，为企业带来了显著的经济效益。

关键词: 在线动态模拟, 复叠式制冷, 节能优化, 数字孪生