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Experiments to populate and validate a processing model for polyurethane foam. BKC 44306 PMDI-10

Mondy, L.A.; Bauer, Stephen J.; Hileman, Michael B.; Thompson, Kyle R.; Smith, David M.; Rao, Rekha R.; Shelden, Bion S.; Soehnel, Melissa M.; O'Hern, Timothy J.; Grillet, Anne M.; Celina, Mathias C.; Wyatt, Nicholas B.; Russick, Edward M.

We are developing computational models to elucidate the expansion and dynamic filling process of a polyurethane foam, PMDI. The polyurethane of interest is chemically blown, where carbon dioxide is produced via the reaction of water, the blowing agent, and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. Here we detail the experiments needed to populate a processing model and provide parameters for the model based on these experiments. The model entails solving the conservation equations, including the equations of motion, an energy balance, and two rate equations for the polymerization and foaming reactions, following a simplified mathematical formalism that decouples these two reactions. Parameters for the polymerization kinetics model are reported based on infrared spectrophotometry. Parameters describing the gas generating reaction are reported based on measurements of volume, temperature and pressure evolution with time. A foam rheology model is proposed and parameters determined through steady-shear and oscillatory tests. Heat of reaction and heat capacity are determined through differential scanning calorimetry. Thermal conductivity of the foam as a function of density is measured using a transient method based on the theory of the transient plane source technique. Finally, density variations of the resulting solid foam in several simple geometries are directly measured by sectioning and sampling mass, as well as through x-ray computed tomography. These density measurements will be useful for model validation once the complete model is implemented in an engineering code.

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TYPE SAND Report YEAR 2014
DOIOSTI

Drop-size distributions and spatial distributions in an annular centrifugal contactor

AIChE Journal

Wyatt, Nicholas B.; O'Hern, Timothy J.; Shelden, Bion S.

Annular centrifugal contactors were developed as single, compact units utilized to transfer desired species between immiscible fluid phases. Critical to understanding the mass-transfer characteristics in the annular mixing region is a clear picture of the distribution of droplet sizes of the fluids involved. To date, very little experimental data appears in the literature. We fill that void by using laser fluorescence and optical methods to directly observe and measure drop-size distributions for a silicone oil/water system in a centrifugal contactor. The shape and characteristics of the log-normal distributions, including the Sauter mean diameter and distribution means, are elucidated in terms of rotor speed and organic phase fraction. The size distribution of entrained air bubbles is also examined. The results presented here will be invaluable in validating and expanding the predictive capacity of the many models that have been developed to describe the flow within these devices. © 2013 American Institute of Chemical Engineers (AIChE).

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TYPE Journal Article YEAR 2013
OSTIScopus
Results 1–25 of 30
Results 1–25 of 30