单相受热管移动参数模型的修正

在单相管移动参数模型的研究中仅根据时间常数来确定移动函数,不能恰当地反映实际状况。该文基于单相管理论传递函数,明确了动态参数在移动函数的选择过程中的决定性意义。借助于解析方法,发现原模型仅仅当动态参数在2左右时适用。对于不同的动态参数,需要采用不同的移动函数。因为动态参数越大则对象的纯延迟越大,所以要求移动函数的变化速度越快。以常用的高精度传递函数的响应曲线为参考比较了多种移动函数的特性。给出了由动态参数决定的移动函数的具体选取方式。结果表明,修正后的模型可以更准确地描述常用热工设备的运行状况。

Moving parameter model for single phase flow in heated pipes

In the moving parameter model for single phase flow in heated pipes, the moving parameter function is only a function of the system characteristic time, so it can not accurately describe the system characteristics. Dynamic variations of the moving parameter function were identified based on a theoretical transfer function for single-phase flows in heated pipes to improve the model. The original model is only applicable when the dynamics parameter is about 2. Different dynamics parameters require different moving parameter functions because the moving parameter function changes faster when the dynamics parameter is larger. Several moving parameter functions were compared with a set of high precision transfer functions with specific moving parameter functions determined by the dynamics parameter. The results show that the modified formulae can better describe the operation of commonly used devices in thermal engineering.