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dc.contributor.authorEstejab, Baharehen_US
dc.date.accessioned2017-09-21T06:00:27Z
dc.date.available2017-09-21T06:00:27Z
dc.date.issued2016-03-29en_US
dc.identifier.othervt_gsexam:7271en_US
dc.identifier.urihttp://hdl.handle.net/10919/79366
dc.description.abstractIn this study, efforts ensued to increase our knowledge of fluidization and gasification behavior of Geldart A particles using CFD. An extensive Eulerian-Eulerian numerical study was executed and simulations were compared and validated with experiments conducted at Utah State University. In order to improve numerical predictions using an Eulerian-Eulerian model, drag models were assessed to determine if they were suitable for fine particles classified as Geldart A. The results proved that if static regions of mass in fluidized beds are neglected, most drag models work well with Geldart A particles. The most reliable drag model for both single and binary mixtures was proved to be the Gidaspow-blend model. In order to capture the overshoot of pressure in homogeneous fluidization regions, a new modeling technique was proposed that modified the definition of the critical velocity in the Ergun correlation. The new modeling technique showed promising results for predicting fluidization behavior of fine particles. The fluidization behavior of three different mixtures of coal and poplar wood were studied. Although results indicated good mixing characteristics for all mixtures, there was a tendency for better mixing with higher percentages of poplar wood. In this study, efforts continued to model co-gasification of coal and biomass. Comparing the coal gasification of large (Geldart B) and fine (Geldart A) particles showed that using finer particles had a pronounced effect on gas yields where CO mass fraction increased, although H2 and CH4 mass fraction slightly decreased. The gas yields of coal gasification with fine particles were also compared using three different gasification agents. Modeling the co-gasification of coal-switchgrass of both fine particles of Geldart A and larger particles of Geldart B showed that there is not a synergetic effect in terms of gas yields of H2 and CH4. The gas yields of CO, however, showed a significant increase during co-gasification. The effects of gasification temperature on gas yields were also investigated.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectBiomassen_US
dc.subjectBinary mixtureen_US
dc.subjectCoalen_US
dc.subjectDrag modelsen_US
dc.subjectFluidizationen_US
dc.subjectGasificationen_US
dc.subjectCo-gasificationen_US
dc.subjectMixtureen_US
dc.titleHydrodynamic and gasification behavior of coal and biomass fluidized beds and their mixturesen_US
dc.typeDissertationen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMechanical Engineeringen_US
dc.contributor.committeechairBattaglia, Francineen_US
dc.contributor.committeememberLuttrell, Gerald H.en_US
dc.contributor.committeememberHuxtable, Scott T.en_US
dc.contributor.committeememberLattimer, Brian Y.en_US
dc.contributor.committeememberBayandor, Javiden_US


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