EVALUATION OF CRUDE OIL FOULING FORMATION IN A HEAT EXCHANGER WITH TWISTED TAPE INSERTS

This paper aims to give a new analysis approach of the crude oil fouling phenomenon through CFD. Heat exchangers are analyzed in order to evaluate the effects of the presence of turbulators on thermal resistance. In particular, it will be investigated if fouling increases in presence or in absence of mechanical inserts inside tubes for heat exchangers, performing transient 3-D and 2-D simulations, paying attention to some parameters to which fouling is tied. The inserts analyzed are twisted tapes. They are static mixers used to improve thermal performances by enhancement of heat transfer coefficient and generation of a secondary swirl flow. The chemical reactions that generate fouling in the case of crude oil are those of asphaltene and salt. To understand the concentrations of species in each point of the tube, a species transport model is set in the CFD analysis. Then, to describe the chemical reaction fouling phenomena, and appreciate its dependence on time, a multicomponent approach for a binary diffusion coefficient is used. The main aim of the work is to evaluate the influence of twisted tapes on fouling and, therefore, on the resulting thermal resistance, comparing the case in question with a classic heat exchanger without inserts.