Numerical prediction of a nusselt number equation for stirred tanks with helical coils

Abstract

A methodology to obtain a Nusselt correlation for stirred tank reactors is presented. The novelty of the approach is the use of a validated computational model to obtain the heat‐transfer coefficients. The advantages of this new approach are many, including the possibility of testing different heat‐transfer configurations to obtain their Nusselt correlation without performing experimental runs. Physical phenomena involved was represented both qualitatively and quantitatively. The classical experimental work of (Oldshue and Gretton, Chem Eng Prog. 1954;50(12):615–621) illustrates the procedure. A sufficient number of virtual points in the whole range of the Reynolds number should be obtained. Results strongly depend on mesh refinement in the boundary layer, so a procedure is suggested to guarantee heat‐transfer coefficients are accurately estimated. The final Nusselt correlation was compared against all the 107 experimental points of the work by (Oldshue and Gretton, Chem Eng Prog. 1954;50(12):615–621), and an average deviation on the results of 10.7%. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3912–3924, 2017

An Investigation of the Heat Transfer Performance of Dual Improved Intermig Impellers in a Stirred Tank With an Inner Heating Coil

“…Considering the accuracy of this model, the whole reactor is modelled as the system investigates rotational periodicity of heat transfer. (Prada and Nunhez, 2017) The area inside the stirred tank is divided, and an unstructured mesh is used to further divide the tank. To improve the mesh quality in the impeller area, the meshes for the impellers and the stirring shaft are refined in advance by the software Gambit.…”

Evaluation of Fluid Flow Velocity Variations on the Plate Heat Exchanger Performance

“…In the industrial world, increasing the efficiency of a technology is needed because the equipment that operation continuously. In conditions where the optimum reaction temperature of the machine or equipment is not reached, heating or cooling is necessary to increase the reaction efficiency and ensure the safety of the equipment during operation [1].…”

“…a. Heat transfer rate on the cold side ( cold) (1) b. Heat transfer rate on the hot side ( hot) If the mass flow rate of a heat exchanger is not known, it could to determined using the formula:…”

Friction Factor Distribution at the Side Wall of a Turbulent Agitated Vessel with Baffles Using a MAXBLEND Impeller

“…Helical coils are typically used to control the temperature in the tank for their high thermal efficiency. Heat transfer in the agitated tank with helical coils has been experimentally and numerically studied with Newtonian and non-Newtonian fluids. − On the other hand, the heat transfer through the sidewall of the tank is often conducted in order to simplify the geometry of the tank and for the ease of cleaning. Heat transfer coefficients of the tank wall have been, therefore, investigated by many researchers. − One of the most common estimations of heat transfer in the turbulent regime is the semiempirical nondimensional equation (eq ) in the form of the Nusselt number. The coefficient K depends on the impeller configuration, so many values have been proposed for various impellers. − Hiraoka et al evaluated the heat transfer coefficient near the sidewall of the vessel according to the Chilton–Colburn analogy in the fully turbulent regime as follows: Shiobara et al studied the similarity of heat and momentum transfer at the sidewall of the unbaffled vessel and proposed the following correlation equation in the form of the j -factor. Equations and indicate that the agitated vessel has a certain analogy between thermal boundary layers at the sidewall, and the heat transfer coefficient there can be estimated by the friction factor calculated by the power consumption of the impeller.…”