(227y) Heat Transfer Analysis of a Non-Newtonian Fluid Flowing through a Plate Heat Exchanger Using CFD

Heat transfer analysis of a non-Newtonian fluid flowing through a Plate Heat Exchanger using CFD

 Oscar M. Hernández-Calderón^1*, Maritza E. Cervantes-Gaxiola¹, Eusiel Rubio-Castro¹, Erika Y. Rios-Iribe¹,  José J. Caro-Corrales¹

¹Chemical and Biological Sciences Department, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa 80013, Mexico

^*omhc@uas.edu.mx

In this work, the moment and heat transfers of a non-Newtonian fluid flowing in steady laminar regime through a plate heat exchanger at constant wall temperature is studied using CFD. A configuration of flat plates in parallel flow is used with and without baffles. The effect of different number of plates and different distance between plates on the heat transfer and the pressure drop are investigated over the Reynolds number range of 0.2-600. It was found that the relationship between the heat transfer rate and the pumped power for all the configurations of flat plates without baffles is practically independent of the number of plates and the distance between plates. Data reduction is applied to the CFD data; and for all cases, a good agreement is found between the calculated generalized Reynolds and friction factor, and the theoretical relationship (f = 16/Re) over the Reynolds number range of 0.2-20. For all Reynolds numbers investigated, an empirical correlation of the friction factor as a function of the generalized Reynolds number and the ratio between the hydraulic characteristic length and the plate size is developed. From an analysis carried out on the flow between two plates, it is found that the dependence of the Nusselt number on the Péclet number is exponential and dependent on the distance between plates: Nu α Pe^0.296; however, for the configurations of flat plates with baffles at Péclet numbers greater than 30'000, the relationship between the Péclet number and the Nusselt number is given by Nu α Pe^0.958. Thus, it is possible to indicate that although the flow pattern inside the exchanger is highly complex, under a proper definition of the hydraulic characteristic length it is possible to establish simple correlations between the major dimensionless numbers that characterize the behavior of the heat and moment transfers in a plate heat exchanger.