Design of Heat Transfer Surfaces in Agitated Vessels

Abstract

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.

Net Zero Roadmap Modelling for Sustainable Dairy Manufacturing and Distribution

“…Where, m pr is the total mass of raw milk in the cooling tank, C prm is the specific heat capacity of raw milk stored, T rm,i the initial temperature of raw milk loaded in the cooling tank, and T cs the cold-storage temperature [60,61].…”

Review Heat Transfer of Non-Newtonian Fluids in Agitated Tanks

“…The apparent viscosity can be calculated from Eqs. (1) and (2) replacing the shear stress term by the following definition (Eq. (3)):…”

“…Rosa and Moraes [1] presented a deduction from the first law of thermodynamics applied to a tank in Newtonian fluid agitation for transient regime operations; however, at that moment the effect of viscous dissipation in the process as described in Item 2 of this text was not considered, which for non-Newtonian liquids is indispensable.…”

“…The agitation and mixing of liquids are an operation commonly used in chemical, petrochemical, food and pharmaceutical processes. In general, the aforementioned operation is performed in tanks (usually cylindrical shape) with mechanical impellers [1]. Generally, agitation refers to forcing a fluid by mechanical means to flow in circulatory or similar pattern inside a vessel [2].…”

“…Rosa and Moraes [1] discussed in detail the main equations used for the coefficient h i in tanks with agitation, so in this topic, the main discussion will be in relation to the external convection coefficient (h o ).…”