應用共軛梯度逆向熱傳預測法測定果蔬之熱擴散係數

Determination of Thermal Diffusivity of Vegetables by the Conjugate Gradient Method of Inverse Heat Transfer Problem

林宜弘(Yi-Hong Lin) ； 廖建貴(Chien-Kuei Liaw)

《農業機械學刊》 4卷2期 (1995/06) Pp. 27-36

https://doi.org/10.30062/JAM.199506.0003

摘要

本文應用逆向熱傳問題參數預測法來預測果蔬農產品的熱擴散係數，文中採用共軛梯度法配合有限差分數值方法來解一維熱傳遞理論的簡單數學模式與邊界條件，所預測結果證實只要熱源表面附近單一量測位置即可正確預測值，且在計算過程對初始猜測值相當不敏感，收斂速度相當快，並且十分可靠。從結果分析顯示，在能順利預測的情況下，欲提高預測準確度必須降低量測系統的量測誤差、延長量測時間、增加埋設點位置距熱源位置的距離、提高熱源表面溫度與物品初始溫度的差距。

關鍵字

共軛梯度法 ； 逆向熱傳問題 ； 果蔬 ； 熱擴散係數

並列摘要

This paper applied the parameter estimation of inverse heat conduction problem to determine the thermal diffusivity of vegetables. The physical mathematical model of one dimensional heat conduction associated with simple boundary conditions were solved to predict the thermal diffusivity by means of finite difference method in conjuction with conjugate gradient method. The results of illustrative example validate that good estimation were obtained by only taking single embeded measurement point adjacent to the position of heating surface. Another good performance includes the high converged speed of iterative computation, the apparent insensitivity of initial guess for prediction and the high reliability of estimated value. Futher, the results clearly demonstrate from testing analysis that under the predictable circumstances, the high accuracy of predicted value will be perserved by following:(1)reducing the expermental measurement errors,(2)enlonging the measurement time,(3)locating the embeded measurement point far from the heating surface,(4)raising the deviation of heating surface temperature and initial temperature.

並列關鍵字

Conjugate gradient method ； Inverse heat conduction problem ； Vegetables ； Thermal diffusivity