Indirect estimation of unsteady temperature profiles by means of a numerical method based on finite approximations

In this paper we present the results of a short phenomenological investigation on indirect heat transfer. The aim of this investigation is to gain a better understanding towards the service life of a solid structure subject to thermal stresses (e.g., a pipeline). A numerical scheme, based on finite approximations, is used to estimate temperature profiles at an inaccessible wall. Such a situation occurs in a nuclear power plant, for example, when monitoring pipelines subject to thermal stresses. Due to the operating conditions (e.g., high pressure and/or high temperatures) it is not always feasible to measure the temperature at each location of the pipeline. Therefore, the temperature is measured at a certain location (for instance, at an outer surface) and the temperature at the inner surface, must be estimated. The word estimate is used to indicate that an exact solution at the given conditions is not known, or is not suitable for use in practice. Thus, the estimation of the temperature can be seen as an indirect method for the prediction of temperature profiles. Accurate estimation of the temperature profiles relies on the quality of the measurements. This serves as a basis for monitoring and predicting the expected service life in systems such as pipelines. (author)