紧凑式换热器性能瞬变测试的非线性参数估计

Nonlinear parameter estimation method for transient test of compact heat exchangers

提出了一种紧凑式换热器平均表面传热系数瞬变测试方法.只需通过测定流体出口温度变化,用Levenberg Marquardt非线性曲线拟合,同时对理论模型中的流体进口温度变化时间常数τ+和传热单元数NTU进行参数估计.敏感性分析和具有测量噪声的数值仿真实验表明,参数估计值具有良好的精度.

A transient testing technique for measuring average convection heat transfer coefficients of compact heat exchangers is suggested. The experimental exit fluid temperature history is measured and matched with theoretical curves. The time constant of the inlet fluid temperature τ^＋ as well as the number of heat transfer units NTU can be determined with Levenberg-Marquardt method as a process of nonlinear parameter estimation. Both sensitivity analysis and numerical experiments with simulated measurements containing random errors are performed. It is shown that the method in the present investigation provides accurate estimates for both two parameters,NTU and τ^＋.