A dynamic, distributed model of shell-and-tube heat exchangers undergoing crude oil fouling / Francesco Coletti in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp.4515–4533 Titre : A dynamic, distributed model of shell-and-tube heat exchangers undergoing crude oil fouling Type de document : texte imprimé Auteurs : Francesco Coletti, Auteur ; Sandro Macchietto, Auteur Année de publication : 2011 Article en page(s) : pp.4515–4533 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dynamic Heat exchangers Résumé : Fouling in refinery preheat trains causes major energy inefficiencies, resulting in increased costs, greenhouse gas emissions, maintenance efforts, and safety hazards. Fouling deposition is not well understood, and current exchanger design and monitoring practices neglect the local effects and dynamics of fouling, in favor of lumped, steady-state, heuristic models (e.g., Tubular Exchanger Manufacturers Association (TEMA) fouling factors). In this paper, a dynamic, distributed model for a multipass shell-and-tube heat exchanger undergoing crude oil fouling is proposed. The model calculates fouling rates as a function of local conditions and time. It accounts for heat exchanger geometry, variation of oil physical properties with temperature, local accumulation of fouling deposits, and their structural change over time (aging). The interaction between fouling growth and fluid dynamics inside the tubes is accounted for by solving a moving boundary problem. Moreover, a procedure to analyze refinery data and support the estimation of a set of model parameters has been established. The model is validated using data from an ExxonMobil refinery and shows excellent agreement (less than 2% error) with primary plant measurements even when it is tested for its predictive capabilities over long periods (i.e., 1 year). It is concluded that the model can be used with confidence to identify and predict the fouling state of exchangers, to assess economic losses due to fouling, to support operating decisions such as planning of cleaning schedules, and to assist in the design and retrofit of heat exchangers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901991g [article] A dynamic, distributed model of shell-and-tube heat exchangers undergoing crude oil fouling [texte imprimé] / Francesco Coletti, Auteur ; Sandro Macchietto, Auteur . - 2011 . - pp.4515–4533. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp.4515–4533 Mots-clés : Dynamic Heat exchangers Résumé : Fouling in refinery preheat trains causes major energy inefficiencies, resulting in increased costs, greenhouse gas emissions, maintenance efforts, and safety hazards. Fouling deposition is not well understood, and current exchanger design and monitoring practices neglect the local effects and dynamics of fouling, in favor of lumped, steady-state, heuristic models (e.g., Tubular Exchanger Manufacturers Association (TEMA) fouling factors). In this paper, a dynamic, distributed model for a multipass shell-and-tube heat exchanger undergoing crude oil fouling is proposed. The model calculates fouling rates as a function of local conditions and time. It accounts for heat exchanger geometry, variation of oil physical properties with temperature, local accumulation of fouling deposits, and their structural change over time (aging). The interaction between fouling growth and fluid dynamics inside the tubes is accounted for by solving a moving boundary problem. Moreover, a procedure to analyze refinery data and support the estimation of a set of model parameters has been established. The model is validated using data from an ExxonMobil refinery and shows excellent agreement (less than 2% error) with primary plant measurements even when it is tested for its predictive capabilities over long periods (i.e., 1 year). It is concluded that the model can be used with confidence to identify and predict the fouling state of exchangers, to assess economic losses due to fouling, to support operating decisions such as planning of cleaning schedules, and to assist in the design and retrofit of heat exchangers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901991g

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Optimal design of clinical tests for the identification of physiological models of type 1 diabetes mellitus / Federico Galvanin in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1989–2002 Titre : Optimal design of clinical tests for the identification of physiological models of type 1 diabetes mellitus Type de document : texte imprimé Auteurs : Federico Galvanin, Auteur ; Massimiliano Barolo, Auteur ; Sandro Macchietto, Auteur Année de publication : 2009 Article en page(s) : pp. 1989–2002 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Type 1 diabetes mellitus Artificial pancreas Dynamic simulation model Glucose-insulin system Résumé : Type 1 diabetes mellitus is a disease affecting millions of people worldwide and causing the expenditure of millions of euros every year for health care. One of the most promising therapies derives from the use of an artificial pancreas, based on a control system able to maintain the normoglycaemia in the subject affected by diabetes. A dynamic simulation model of the glucose−insulin system can be useful in several circumstances for diabetes care, including testing of glucose sensors, insulin infusion algorithms, and decision support systems for diabetes. This paper considers the problem of the identification of single individual parameters in detailed dynamic models of glucose homeostasis. Optimal model-based design of experiment techniques are used to design a set of clinical tests that allow the model parameters to be estimated in a statistically sound way, while meeting constraints related to safety of the subject and ease of implementation. The model with the estimated set of parameters represents a specific subject and can thus be used for customized diabetes care solutions. Simulated results demonstrate how such an approach can improve the effectiveness of clinical tests and serve as a tool to devise safer and more efficient clinical protocols, thus providing a contribution to the development of an artificial pancreas. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801209g [article] Optimal design of clinical tests for the identification of physiological models of type 1 diabetes mellitus [texte imprimé] / Federico Galvanin, Auteur ; Massimiliano Barolo, Auteur ; Sandro Macchietto, Auteur . - 2009 . - pp. 1989–2002. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1989–2002 Mots-clés : Type 1 diabetes mellitus Artificial pancreas Dynamic simulation model Glucose-insulin system Résumé : Type 1 diabetes mellitus is a disease affecting millions of people worldwide and causing the expenditure of millions of euros every year for health care. One of the most promising therapies derives from the use of an artificial pancreas, based on a control system able to maintain the normoglycaemia in the subject affected by diabetes. A dynamic simulation model of the glucose−insulin system can be useful in several circumstances for diabetes care, including testing of glucose sensors, insulin infusion algorithms, and decision support systems for diabetes. This paper considers the problem of the identification of single individual parameters in detailed dynamic models of glucose homeostasis. Optimal model-based design of experiment techniques are used to design a set of clinical tests that allow the model parameters to be estimated in a statistically sound way, while meeting constraints related to safety of the subject and ease of implementation. The model with the estimated set of parameters represents a specific subject and can thus be used for customized diabetes care solutions. Simulated results demonstrate how such an approach can improve the effectiveness of clinical tests and serve as a tool to devise safer and more efficient clinical protocols, thus providing a contribution to the development of an artificial pancreas. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801209g

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