An Experimental-Theoretical Study on Batch (Static) Sublimation and Derivation of a Correlation for its Heat Transfer Coefficient

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Mottafegh, Amir Reza | 2019

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 53383 (46)
University: Sharif University of Technology
Department: Energy Engineering
Advisor(s): Otukesh, Mohammad
Abstract:
The major features of batch sublimation were investigated in an experimental-theoretical study. An experimental setup with real-time displays, sublimated dry ice blocks of different sizes, with circular or rectangular geometries. When temperature of hotplate was changed from -30 to 200 oC, heat transfer coefficient “hsub” decreased from 126 to 70 W/m2K, while thermal flux increased, linearly. Weight and area of the block had a positive/negative effects on “hsub”, respectively. In theoretical part, at first, two “linear-gradient” and “cubic” models were developed by a combined mass-momentum-energy balance. The latter used Von Karman temperature profile, and in cases of circular and rectangular geometries could estimate “hsub” with 17.8 and 13.5 % average error. Linear-gradient was analytic, with similar accuracy in the circular case. The second part of modelling focused on modification of Langmuir molecular equation for sublimation rate. Simultaneous application of the obtained equations with “linear-gradient” model reduced average error to 6.87%
Keywords:
Outgassing ; Uranium Hexafluoride ; Heat Transfer Coefficient ; Modeling ; Langmuir Monolayer ; Experimental Studies ; Model Development ; Dry Ice

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