In a previous work, Spogis and Nunhez (2009) proposed an optimization procedure for mixing tanks in which optimization methods inside modeFRONTIER were used with a computational fluid dynamics (CFD) model. The optimization software was used in conjunction with ANSYS CFX tools in order to obtain an...

In a previous work, Spogis and Nunhez (2009) proposed an optimization procedure for mixing tanks in which optimization methods inside modeFRONTIER were used with a computational fluid dynamics (CFD) model. The optimization software was used in conjunction with ANSYS CFX tools in order to obtain an optimal design of a high efficiency impeller for solid suspension. This procedure linking optimization methods is not new and has been used, for example, in the aerospace industry with a view to improve the shape of airplane wings (Makinen et al., 1999), in the improvement of diesel engines (Shi and Reitz, 2008) and to improve process equipment such as heat exchangers (Foli et al., 2006). Spogis and Nunhez (2009) followed the idea and proposed the use of CFD along with an optimization model for stirred tanks for the first time. The impeller proposed in that contribution has mechanical and design problems that make it impossible for this impeller to be produced for industrial use. The power number of the impeller proposed by Spogis and Nunhez (2009) is 0.05 and the flow number is 0.2. This means that an industrial impeller, in order to pump well inside the tank needs an impeller rotating at a high speed which, in turn, can cause the impeller to work at unstable conditions. Even though the power consumption is very low, the effective flow number is also low. An industrial impeller needs a high flow number and Power number higher than 0.2 in order to pump well at low speeds and still present a low power draw. This further refinement was implemented and, even though the procedure is similar to the one presented by Spogis and Nunhez (2009), the new impeller configurations is completely different. 1 and 2 - Authors to whom all correspondence should be addressed

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