Dinâmica, otimização e controle de processos de fermentação em estado sólido : desenvolvimento de metodologias em escala laboratorial
Fonseca, Rafael Frederico
MetadataShow full item record
Solid-state fermentation is characterized by the growth of microorganisms in absence of free water. In one hand, it is advantageous because simulates their natural environment, enabling the use of agro industrial residues in natura. On the other hand, it limits heat transfer between elements, restricting control over the temperature of the medium. In fact, the microbial growth and the product formation dynamics are directly affected by the environmental conditions and variations can be harmful to the process productivity. As a consequence, the temperature increase caused by metabolic heat needs to be avoided. Studies concerning the microbial dynamics dealing with these variations are scarce. Moreover, it was not found any control laws, with guarantee of stability, which was designed for a reference tracking and to minimize the disturbances effects. Thus, two fronts need to be addressed for the solid-state fermentation viability: the development of a mathematical model able to estimate the effects of environmental changes in the process; and a temperature control system able to handle the heat from microbial metabolism. The model was used in a computational algorithm in order to determine if there was a temperature profile that would be more favorable to the products formation. In this work two control laws were studied, a proportional integrative, because it is the most widespread in the industry, and a model base predictive controller, because of its multivariable control versatility. Both control laws were simulated and then implemented in an eleven liters agitated drum bioreactor. Some of the various methods for PI controller parameters settings had their performance and relative stability requirement evaluated. The one that was proved stable was implemented in the bioreactor. Due to the uncertainties of the fermentation process, a self-adjustment mechanism was added to the predictive controller, in spite of the developed mathematical model, in order to avoid some estimation mistakes caused by some non-estimated states of the real process. The controller achieved an adequate performance with this approach. The results showed that the microorganisms were more efficient at a constant 32°C temperature. In addition, both developed controllers presented appropriate results facing the fermentation process requirement, with mean deviances from the referential temperature below 0,6°C and a maximum error of 2,8°C.
Showing items related by title, author, creator and subject.
A modelagem de gráficos de controle de aceitação condicionados aos índices de capabilidade de processos : uma abordagem prática e econômica Costa, Fabrício martins da (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Engenharia de Produção - PPGEP, Câmpus São Carlos, 07/07/2017)Modified and acceptance control charts allow a new approach to statistical process monitoring. This research topic is little explored in the academic world, thus, this thesis contributes to the advancement of statistical ...
Oshiro, Claudia Kami Bastos (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Educação Especial - PPGEEs, , 30/08/2004)This study investigated responding by exclusion , which has been demonstrated as a robust behavioral process, consisting in the selection of an undefined comparison stimulus, when the sample is also an undefined stimulus ...
Condições que favorecem ou desfavorecem a aprendizagem relacional em crianças com histórico de fracasso escolar Arantes, Ana Karina Leme (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Educação Especial - PPGEEs, , 28/02/2008)The stimulus equivalence concept has been used by behavior analysts as an instrument to systematic verifications of new and complex repertories, offering an operational specification of symbolic behavior and distinguishing ...