Introducing a holistic approach to model and link fouling resistances

Abstract

AbstractFouling is the unwanted deposition of soils on heat transfer surfaces and is a major challenge for industry and has been s subject to scientific investigations for decades, still being an unsolved problem for many applications. A fouling situation is commonly quantified with the thermal fouling resistance describing the integral fouling behavior of an apparatus. Modeling of this quantity is a permanent subject to research. This contribution presents the basics of an expanded consideration by introducing a holistic approach to model and link fouling resistances based on the extension of previous work in this field. A thermal and a mass based approach to calculate fouling resistances are considered integrally and locally. This will provide a detailed knowledge of the fouling behavior. Various variables are needed for modeling the different fouling resistances. Therefore, both experimental and analytical methods have to be applied to obtain the required data regarding local differences of crystallization deposits within double-pipe heat exchangers. Here the planned experimental and analytical approaches to receive all the required input data are described, also presenting the required test equipment briefly. Core equipment is a test rig equipped with double pipe heat exchangers, which allows the measurement of thermal and fluid flow related values and provides samples for the analysis of the fouling deposits. Furthermore, the aim of the new modeling concept is to link integral and local fouling resistances by taking into account locally varying parameters regarding the fouling layer. In order to allow for that, a recalculation of the thermal fouling resistance into a corrected version by considering heat transfer enhancing effects attempts to correlate with the mass based approach in a first step. In the end, the holistic modelling approach is presented.