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A simulation program based on a control volume analysis has been used in the evaluation of the (ε, NTU) relationship for coils of complex geometry and flow arrangement. The simulation program has been evaluated through simple geometry and flow arrangement coils. The program results compare very well with correlations for simple cross flow coils, and a number of rows up to four. It has also been determined that closed form correlations developed for coils of an infinite number of tube rows are inadequate for those with number of rows in the range between 5 and 10. In addition, it has been found that closed form (ε, NTU) correlations for cross flow coils with the same tube arrangement and number of rows might lead to inaccuracies higher than 10% in the evaluation of the effectiveness of coils of complex flow arrangement.

Submitted by leitem@stj.jus.br (leitem@stj.jus.br) on 2019-08-27T18:56:42Z No. of bitstreams: 2 adjudicacao_compulsoria_helio.pdf: 1574658 bytes, checksum: 969ebc717efb84190b2f99a018d75c8a (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Approved for entry into archive by Roberta Marins (rmarins@stj.jus.br) on 2019-08-30T20:50:15Z (GMT) No. of bitstreams: 2 adjudicacao_compulsoria_helio.pdf: 1574658 bytes, checksum: 969ebc717efb84190b2f99a018d75c8a (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Made available in DSpace on 2019-08-30T20:50:15Z (GMT). No. of bitstreams: 2 adjudicacao_compulsoria_helio.pdf: 1574658 bytes, checksum: 969ebc717efb84190b2f99a018d75c8a (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Previous issue date: 1985

Made available in DSpace on 2014-06-11T19:26:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-12Bitstream added on 2014-06-13T20:54:32Z : No. of bitstreams: 1 souza_mp_me_bauru.pdf: 1121017 bytes, checksum: 8ed8fe65e5cd46111ec16064bc42b009 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) No presente trabalho desenvolve-se um estudo de modelagem matemática e simulação numérica do escoamento bifásico gás-sólido em leito fluidizado borbulhante. Utiliza-se o modelo Euleriano de duas fases separadas formulando o tensor das tensões da fase sólida através da teoria cinética dos escoamentos granulares. As simulações numéricas são realizadas através do código fonte MFIX (Multiphase Flow with Interphase eXchanges) desenvolvido no NETL (National Energy Technology Laboratory). Os resultados de simulação numérica são avaliados por meio da análise da influência dos seguintes parâmetros: malha computacional e esquemas de discretização dos termos convectivos das equações de conservação. Com base nos estudos teóricos e resultados obtidos durante o trabalho conclui-se que esquemas de primeira, tais como FOUP são altamente difusivos, já os resultados obtidos utilizando o esquema de alta ordem, Superbee, produziu resultados de melhor qualidade para as malhas testadas neste trabalho. Além disso, os resultados mostraram-se bastante dependentes do tamanho da malha computacional. In the present work is described a mathematical model and numerical simulation of gas-solid two-phase flow in a bubbling fluidized bed. It is used the Eulerian gas-solid two-fluid model and the solid phase stress tensor is modeled considering the kinetic theory of granular flows. The numerical simulations were developed using the MFIX (Multiphase Flow with Interphase eXchanges) code developed in NETL (National Energy Technology Laboratory). The numerical diffusion is analyzed considering a single bubbling detachment and its movement process in a two-dimensional bubbling fluidized bed using the bubble shape as a metric for results description. The influence of computacional grid it is also analyzed. It is concluded that SuperBee scheme produces the better results and analysis about estimating uncertainty in grid refinement should be studied.

Made available in DSpace on 2014-06-11T19:25:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-12Bitstream added on 2014-06-13T18:26:27Z : No. of bitstreams: 1 mineto_at_me_bauru.pdf: 1189778 bytes, checksum: 6d950fce04e9cbf0b24c319a7847ead4 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) No presente trabalho desenvolve-se um estudo de modelagem matemática e simulação numérica do escoamento gás-sólido em um leito fuidizado borbulhante. É apresentado o modelo hidrodinâmico, A, para escoamentos bifásicos gás-solido considerando a Teoria Cinética dos Escoamentos Granulares. É usado o modelo Euleriano de duas fases separadas considerando a modelagem do tensor das tensões da fase sólida através do atrito entre as partículas e da teoria cinética dos escoamentos granulares. O código fonte MFIX (Multiphase Flow with Interphase eXchanges) desenvolvido no NETL (National Energy Technology Laboratory) é utilizado para as simulações numéricas. Os resultados de simulação são obtidos resolvendo a temperatura granular algebricamente ou através de uma equação diferencial parcial. Obtêm-se resultados mais realísticos no uso da EDP com condição de contorno de deslizamento parcial na parede. Uma variação no diâmetro das partículas (partículas do grupo B e do grupo A/B) é investigada, concluindo-se que deve ser acrescentado ao código MFIX outros parâmetros físico para simulações com partículas do grupo A/B. In the present work is described a mathematical model and numerical simulation of gas-solid flow in the bubbling fluidized bed. It is presented the hydrodynamic model, A, for gas-solid flow considering the Kinetic Theory of Granular Flows. It is used the two fluids Eulerian model where the solid phase stress tensor is modeled considering the friction between the particles and the kinetic theory of granular flows. The code MFIX (Multiphase Flow with Interphase eXchanges) developed in NETL (National Energy Tecnology Laboratory) is used for numerical simulations. The results are obtained with the compute of the granular temperature using a partial differential equation or an algebraic expression. It was obtained more realistic results when is used a PDE with boundary conditions of the partial slip. A variation in the diameter of the particles (particles in Group B and Group A/B) it is analyzed. It is also concluded that should be added to the code MFIX other physical parameters for simulations with particles of group A/B.