Exergo-economic optimization of the operation of a heat exchanger subjected to fouling

The goal of this work is to study the sensitivity of the parameters over the optimal duration of operation of a concentric exchanger bi-tube. To know: the dynamic optimization of the operation of a heat exchanger subjected to a fouling by considering the exergoeconomic criterion. Indeed, the exergo economy offers additional possibilities of optimization compared to the conventional methods on the first principle of thermodynamics, because it allows to associate the irreversibilities to the economic aspects. The model that we propose is a compromise between the aspects exergetic and economic and makes it possible to determine one optimal operation life before the stopping of the exchanger for maintains. These economic aspects take into account the capital cost related on the purchase and the installation of the exchanger, the cost of maintenance related to the cleaning of the exchanger, and the economic losses caused by the malfunction of the heat exchanger. Different adimensional parameters were introduced into the model with an aim of evaluating the parametric sensitivity of the operation lifet_1. The results show a strong influence of the parameters over the operation life. These parameters are : β_cowhich represents report/ratio calorific initial of fluids, X_ewhich is related to the number of units of transfer of reference of the external wall of the tube, A^'which defines the coefficient of surface convective exchange external in the clogged side associated the thermal resistance of the material, A^''which represents the external coefficient of exchange convectif surface at the side fouling associated the asymptotic resistance of fouling of material, Lthe report/ratio of the internal ray, represents here on the external ray of the exchanger. It is related to the geometry of the exchanger, Hrepresents the report/ratio of the surface coefficients of convectifs exchange andτ_erepresents the time-constant of the asymptotic kinetics with an aim thus of evaluating the parametric sensitivity.