The work presents a comprehensive examination of heat transfer in metal foams supports in order to evaluate the improvements connected with the use of such supports in catalytic reactors. Samples with different conductivity of the solid bulk material, different porosity, and different pore density were investigated to determine and evaluate the role of the different heat transfer mechanisms in such supports. The thermal coefficients were evaluated experimentally, in steady state conditions in a pilot pipe under different flow rates, and with finite volume analysis, in reconstructed 3D models of the foam geometry. Correlations have been proposed for the effective radial conductivity, inside the foam bed, and for the wall heat transfer coefficient, between support and pipe skin. At last the developed correlations have been used to simulate the performances of a steam reforming tubular reactor with foam supported catalyst, the results have been compared with those of a traditional packed bed reactor.
Il lavoro presenta un esame complessivo delle proprietà di scambio termico in schiume metalliche per valutare i miglioramenti connessi con l'utilizzo di tali supporti in reattori catalitici. I campioni, con diversa conducibilità del materiale solido, diversa porosità e densità di pori sono stati studiati per determinare e valutare il ruolo dei diversi meccanismi di trasferimento di calore . I coefficienti termici sono stati valutati sperimentalmente, in condizioni stazionarie all'interno di un tubo pilota in diverse portate, e con l'analisi dei volumi finiti, per modelli 3D costruiti sulla geometria della schiuma. Sono state elaborate correlazioni per la conducibilità effettiva radiale, all'interno del letto schiuma, e per il coefficiente di scambio termico della parete, tra il supporto e la pelle del tubo. Infine le correlazioni sviluppate sono state utilizzate per simulare le prestazioni di un reattore tubulare per steam reforming con catalizzatore supportato su schiuma, i risultati sono stati confrontati con quelli di un reattore a letto impaccato tradizionale.
Heat transfer in structured catalysts for steam reforming
BIANCHI, ENRICO
Abstract
The work presents a comprehensive examination of heat transfer in metal foams supports in order to evaluate the improvements connected with the use of such supports in catalytic reactors. Samples with different conductivity of the solid bulk material, different porosity, and different pore density were investigated to determine and evaluate the role of the different heat transfer mechanisms in such supports. The thermal coefficients were evaluated experimentally, in steady state conditions in a pilot pipe under different flow rates, and with finite volume analysis, in reconstructed 3D models of the foam geometry. Correlations have been proposed for the effective radial conductivity, inside the foam bed, and for the wall heat transfer coefficient, between support and pipe skin. At last the developed correlations have been used to simulate the performances of a steam reforming tubular reactor with foam supported catalyst, the results have been compared with those of a traditional packed bed reactor.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/56665