A numerical study and thermal resistance analysis of heat transfer enhancement in plate heat exchangers

The plate heat exchangers have been widely used in industry. This paper presents a numerical simulation of the fluid flow and heat transfer characteristics in cross-corrugated chevron-type plate heat exchangers and dimpled ones. The variations of the overall Nusselt number, resistance coefficient and integrated heat transfer performance factor with the Reynolds number and the dimple depth are obtained. The results show that under the same conditions, both the Nusselt number and the resistance coefficient of the cross-corrugated chevron-type plate are higher than that of the dimpled one. Thus, from the view of the integrated heat transfer performance, the dimpled plate is better. Furthermore, the integrated factor increases as the dimple depth decreases for the studied seven different dimple depths with the same inlet fluid velocity. It is found that the heat transfer processes in plate heat exchangers can be well described by the concept of generalized thermal resistance. Under prescribed temperature boundary conditions, the heat transfer increases with the decrease of the thermal resistance. Therefore, the generalized thermal resistance can be taken as an evaluation standard for the heat transfer performance of a plate heat exchanger.