Process identification using simultaneous heat and mass transfer
Berg, and Altner, M.
1999 Intern publikation, Process Design Laboratory, Department of Chemical Engineering, ?bo Akademi University, Biskopsgatan 8, FIN-20500 ?bo, FINLAND
Berg, and Altner, M., (1999), "Process identification using simultaneous heat and mass transfer", Intern publikation, Process Design Laboratory, Department of Chemical Engineering, ?bo Akademi University, Biskopsgatan 8, FIN-20500 ?bo, FINLAND.
Abstract:
The objective is to present a process identification method (PIM) which consists of deducing a regression model for heat and mass transfer coefficients in a wetted wall cylinder, e.g. the effect of a tangential inlet and a semi-tangential outlet is analyzed. The PIM is then used to determine heat and mass transfer coefficients (a?a¡ä) from experimental data. The input process variables for the PIM are measurements of both air and water states. The calculations are by nature iterative whilst a heat transfer coefficient guess-value a, is adjusted until both the calculated and measured process variables match each other. The obtained heat and mass transfer coefficients are then transformed to a Nusselt number regression model of the same form, which can be found in literature covering turbulent pipe flow (Jakob 1949, VDI-W?rmeatlas 1953 and Nunner 1956). The deduced process model indicates a relation of high Nusselt numbers compared to Reynolds numbe rs.
All experiments were conducted in a region that covered Reynolds numbers ranging from 60000 to 270000 and the experiments include a significant thermal entrance effect. Some aspects of ionic wind in turbulent flows are also considered. We suggest that an interactive use of the PIM would be a good complement to interprete calculations based on commercial programs for computational fluid dynam ics (CFD).
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