紧凑式换热器表面瞬变测试的敏感性分析和数值模拟

Sensitivity Analysis and Numerical Simulation of Transient Measurements on Compact Heat Exchanger Surfaces

提出了一种考虑纵向导热效应的紧凑式换热器表面平均传热系数瞬变测试方法。根据出口流体温度变化的实测数据,用Levenberg-Marquardt非线性曲线拟合,同时对理论模型中的纵向导热参数lλ和进口流体温度变化时间常数τ+,以及传热单元数Ntu进行参数估计。敏感性分析和具有测量噪声的数值模拟实验表明,待求的反映换热面传热性能的Ntu参数估计值具有良好的精度。

A transient measuring method, for determining the average heat transfer coefficient of a compact heat exchanger＇s surface, is being suggested, which takes into consideration the influence of longitudinal heat conduction. Using outflowing fluid＇s actually measured varying temperature data, a non-linear curve is fitted by the Levenburg- Marquardt method, and simultaneously longitudinal heat conduction parameter λl, the time constant τ^＊ of the entering fluid＇s varying temperature, and the number Ntu of heat transfer units are being estimated for application, in the theoretical model. Both sensitivity analysis and numerical simulation calculation tests, which consider measurements containing random errors, show the satisfactory accuracy of the estimated parameter Ntu we are looking for and, which reflects the heat transfer performance of the heat exchanger surface. Figs 5, tables 2 and refs 9.