Inverse estimation for unknown fouling-layer profiles with arbitrary geometries on the inner wall of a forced-convection duct

In this study, a conjugate gradient method based inverse algorithm is applied to estimate the unknown fouling-layer profile on the inner wall of a duct system using simulated temperature measurements taken on the duct wall. The temperature data obtained from the direct problem are used to simulate the exact temperature measurements. Results show that an excellent estimation on the fouling-layer profile can be obtained for the case without separation bubble. The predictive accuracy, however, slightly deteriorates when there is a separation bubble in the duct flow. The technique presented in this study can be used in a warning system to call for maintenance when the thickness of fouling exceeds a pre-defined criterion.