Heat transfer characteristics of Taylor vortex flow with shear-thinning fluids

Significance 

Pioneered by Taylor in the early twentieth century, Taylor vortex flow has attracted significant research attention in the past few decades. This can be attributed to its vast applications in different chemical processes such as decomposition of biopolymers that requires heating and cooling operations. Generally, the flow between coaxial cylinders comprising of an inner rotating cylinder has been severally investigated thus leading to the discovering of several features associated with Taylor vortex flow. Reynolds number has been largely used in the characterization of flow regimes for investigation of Taylor vortices characterization. However, successful application of the Taylor vortex flow systems in various processes requires the knowledge of Taylor vortex flow under a non-isothermal field.

Presently, several studies on the heat transfer characteristics of Taylor vortex flow are mainly based on the Newtonian fluids. This involves evaluation of the heat transfer coefficients under different operational conditions using different equations correlating the Nusselt number and Reynolds number. For example, researchers have revealed that the increase in the relative buoyancy results in a series of secondary flow regimes induced by classical Taylor vortices. Unfortunately, most of the studies under non-isothermal field are limited to Newtonian fluid systems. Therefore, investigation of heat transfer characteristics of non-Newtonian fluids is highly desirable as they are too important in chemical industries. This should, however, take into consideration the property and influence of shear-thinning phenomenon on the heat transfer characteristic of the Taylor vortex flow.

To investigate the effects of shear-thinning property on the heat transfer characteristics of Taylor vortex flow based on effective Reynolds number, Dr. Hayato Masuda and Professor Makoto Shimoyamada from the University of Shizuoka together with Professor Naoto Ohmura from Kobe University designed an empirical correlation equation between the effective Reynolds number and the Nusselt number in the fluid systems. Specifically, the local distribution of physical properties of non-Newtonian fluid i.e. viscosity, velocity and temperature were determined and compared to those of Newtonian fluids. The fluid flow and the heat transfer were investigated through numerical simulation in a Carreau model by changing the parameter values from 1 to 0.3. The main objective was to accurately reflect the shear-thinning effects. The research work is currently published International Journal of Heat and Mass Transfer.

The flow condition in the experiment was limited to laminar Taylor vortex flow region to enable measurements of the physical properties that are normally difficult to measure experimentally. A decrease in the shear-thinning property resulted in an increase in the local Nusselt number and a corresponding decrease in the temperature and the thickness of the boundary layer. On the other hand, the correlation between the effective Reynolds number and global Nusselt number revealed that the increase in the shear-thinning property led to larger sizes of Taylor vortices. For instance, a global Nusselt number was evaluated within ±10% error for parameter values of 1, 0.7 and 0.5 and ±20% for the parameter value of 0.3. Altogether, the Japanese scientists successfully provided in their study the essential information that will advance understanding of the heat transfer characteristic of Taylor vortex flow with shear-thinning fluids.

Heat transfer characteristics of Taylor vortex flow with shear-thinning fluids - Advances in Engineering

About the author

Hayato Masuda is an assistant professor in the School of Food and Nutritional Science at University of Shizuoka since 2016. Also, he belongs to Complex Fluid and Thermal Engineering Research Center (COFTEC) in Kobe University as an extramural researcher. He received the Ph. D. in Engineering from Kobe University in 2016.

His research interests are chemical/food engineering based on transport phenomena using both experiments and simulations (computational fluid dynamics, CFD). Especially, he has been studied the application of Taylor vortex flow reactor to chemical and food processes. In addition, his recent target is intensification of chemical/food processes accompanied with a viscosity change or phase change.

About the author

Makoto Shimoyamada is a professor in the School of Food and Nutritional Science at University of Shizuoka since 2014. He received the Ph. D. in Agriculture from Tohoku University in 1991.

His research interest is food chemistry and engineering on food processing, especially characterization of protein denaturation and expression of their functional properties under processing.

About the author

Naoto Ohmura is a professor in the Department of Chemical Science and Engineering at Kobe University since 2007. He is also the Dean of Graduate School of Engineering in Kobe University from 2019. He received the Ph. D. in Engineering from Kobe University in 1997.

His main research interest is elucidation and modeling of complex phenomena in chemical processes with the aid of transport science dealing with fluid flow, heat and mass transfer. His recent interest also goes to process intensification and development of novel chemical processes utilizing vortex dynamics, oscillatory flows and ultrasound.

Reference

Masuda, H., Shimoyamada, M., & Ohmura, N. (2019). Heat transfer characteristics of Taylor vortex flow with shear-thinning fluids. International Journal of Heat and Mass Transfer, 130, 274-281.

Go To International Journal of Heat and Mass Transfer

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