The project on heat transfer surfaces in agitated vessels is based on the determination of the heat exchange area, which is necessary to abide by the process conditions as mixing quality and efficiency of heat transfer. The heat transfer area is determined from the overall heat transfer coefficient (U). The coefficient (U) represents the operation quality in heat transfers being a function of conduction and convection mechanisms. The determination of U is held from the Nusselt’s number, which is related to the dimensionless Reynolds and Prandtl’s, and from the fluid’s viscosity relation that is being agitated in the bulk temperature and the viscosity in the wall’s temperature of heat exchange. The aim of this chapter is to present a summary for the literature concerning heat transfer in agitated vessels (equipped with jackets, helical coils, spiral coils, and vertical tube baffles) and also the many parameters of Nusselt’s equation for these surfaces. It will present a numerical example for a project in an agitated vessel using vertical tube baffles and a 45° pitched blade turbine. Subsequently, the same procedure is held with a turbine radial impeller, in order to compare the heat transfer efficiencies.
Part of the book: Heat Exchangers
The heating and cooling of non-Newtonian liquids in tanks with mechanical impellers are operations commonly employed as chemical reactors, heat exchangers, distillers, extractors, thinners and decanters. In particular, the design of heat exchangers (jackets, helical coils, spiral coils and vertical tubular baffles) in tanks requires the prior knowledge of the rheology of the liquid for the calculation of the convection coefficients and the Reynolds number, in order to obtain the area thermal exchange. This chapter aimed to present the basic concepts of tanks with agitation, non-Newtonian liquids, hydrodynamics, heat transfer and, finally, with a practical design example for engineers and undergraduate students.
Part of the book: Heat and Mass Transfer