Influence of capsule length and width on heat transfer in capsule-type plate heat exchangers

Abstract

Capsule-type plate heat exchanger has the advantages of less deposition and low flow resistance. Based on previous research, numerical studies of capsule-type plate heat exchangers with different capsule lengths and widths for the Reynolds number ranging from 600 to 10,000 are performed. The results show that wake vortices, transverse vortices, and longitudinal vortices generate in the channels by the flow shearing and separation. The vortices promote the swirl and flow destabilization, exchange the fluid between the boundary layer and the mainstream, and thus enhance the heat transfer in the capsule-type plate channels. Wake vortices transform to longitudinal vortices with increasing Re. The number of the longitudinal vortices decreases and the size of the longitudinal vortices increases with increasing Re or the decreasing length−width ratio of the capsule. In addition, Nusselt number and friction factor decrease with the increasing length−width ratio of the capsule.