Towards a better understanding of 2D thermal-flow processes in a scraped surface heat exchanger

To optimise and to improve heat transfer in heat exchangers, a special construction with rotational blades, called scraped surface heat exchanger (SSHE), can be applied. Despite SSHE are widely used, thermal-flow processes in these devices are still not well understood. The paper presents and describes a method allowing for precise determination of heat transfer coefficient value in case of periodic heat transfer with mechanical removal of thermal boundary layer. In order to get a better insight into these phenomena, we present numerical study on laminar forced convection in a two-dimensional SSHE model. Transport equations of mass, momentum and energy are solved in a non-inertial coordinate system using finite volume method framework. Numerical model was compared both with available analytical models based on the penetration theory and experimental data available in literature. The main goal is to investigate impact of a wide range of non-dimensional parameters on heat transfer rate. Rotational Reynolds and Prandtl numbers and a non-dimensional gap varied in range 10-1000, 0.71-56.00 and 0.005-0.15, respectively. It was found that the heat transfer rate increases with increasing both Reynolds and Prandtl numbers, and decreases with increasing the non-dimensional gap. The major conclusion resulting from numerical calculations is that the non-dimensional gap plays an important role in the laminar flow regime. (C) 2016 Elsevier Ltd. All rights reserved.