Thermohydraulic Simulation of Heat Exchanger Networks Subjected to Fouling

Abstract Fouling is a complex problem which affects thermal equipment. The deposits over the heat exchanger surface diminish the thermal effectiveness and increase flow resistances. The consequences of fouling are related to important economic penalties, such as, more expensive equipment with larger thermal surfaces, higher energy consumption costs (heat/power), shutdown costs for exchanger cleaning, fluid treatment costs, etc. Despite the considerable research efforts about this subject, the engineering practice is still based on traditional approaches, e.g., fouling factors. Several recent papers have been focused on the schedule optimization of heat exchanger cleaning during a certain time horizon. In this case, optimization algorithms demand the availability of a heat exchanger network model in order to predict the network behavior. Aiming to this important problem, this paper presents the modeling and simulation of heat exchanger networks subjected to fouling. A fundamental aspect of the proposed simulation scheme involves the capacity to represent the network behavior considering heat transfer and fluid flow aspects simultaneously. For a given set of fouling models, it is possible to predict the temperature and flow rate along a heat exchanger network during a certain time span in the future. The model is represented by a set of matrix equations, where the network structure is parameterized using graph theory concepts. The potentiality of the proposed simulation scheme is illustrated through a typical example of an industrial heat exchanger network.