Estudo de mucilagem e fibra naturais (quiabo) como redutores de arrasto em escoamentos com altos números de Reynolds

• Ano de defesa: 2016
• Autor(a) principal: Coelho, Eduardo Calegario
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Engenharia Mecânica; Centro Tecnológico; UFES; Programa de Pós-Graduação em Engenharia Mecânica
• Palavras-chave em Português: Redução de arraste; Biopolímeros; Escoamento turbulento; Reynolds, Número de; Mucilagem; Engenharia Mecânica; 621
• Link de acesso: http://repositorio.ufes.br/handle/10/9736

Drag reduction by injection of high molecular weight polymers into a turbulent flow is an important phenomenon that has been extensively studied by many researchers since it was reported by Toms (1948). The application of this phenomenon represents a great benefit for many industrial processes. However, most polymers commonly used as drag reducing agents are synthetic, have low resistance against the turbulent flow forces and are generally toxic to humans. These facts encourage researchers on the search of natural, more biodegradable and more resistant polymers to replace the artificial ones. In the present work, the drag reduction efficiency of dilute aqueous solutions of a mixture of fibers and polymers extracted from okra pods is investigated. For suchinvestigation, it is used an experimental apparatus, consisting of a system of pipes in series, in which the main section of the test is made of stainless steel with an internal burnishing treatment. This apparatus has a magnetic flow meter and three pressure transducers for acquisition of experimental data and a centrifugal pump, with fixed rotation, promotes the flow. To obtain the test material in this work, a processing methodology for the fruit, which is initially in its natural state, is developed. The results are focused on the analysis of the drag reduction capability of the material at different concentrations. Analyses such as pressure drop and flow increase are also performed, in order to evaluate the efficiency of the solution to degradation. An analysis, in which the absolute ܴܦ values are reorganized, is made and presented as relative drag reduction, ܴܦ′. Considering the fact that it is a natural polymer, which is highly susceptible to biological degradation, a test to evaluate the effect of degradation in the drag reduction capability of the solution is also realized. Since this is a new reduction agent being studied, the material was compared, based on drag reduction capability, with two other materials already widely used, which are, Xanthan Gum, a natural and rigid polysaccharide, and Polyethylene Oxide, a synthetic flexible polymer. Finally, solutions of mixtures of okra fibers and polymers and Polyethylene Oxide are made and tested, which exhibit interesting results associated with synergetic effects. The results confirm the efficiency and applicability of okra polymers and fibers as good drag reduction agents