Hexagonal and Mixed Arrays of Flow Channel Design in Counterflow Heat Exchanger

In this research project we show the advantage of morphing the flow channel design to more complicated arrays in order to enhance the flow and thermal characteristics in counterflow heat exchanger. The free pursuit for the optimal geometry of flow channel cross-sections will be investigated toward meeting two objectives simultaneously: lower longitudinal (along the flow direction) flow resistances and lower perpendicular (channel to channel) thermal resistance. For diverse array of channels, we use an analytical model, i.e., scale analysis, to evaluate the fluid flow performance and numerical model (CFD) to analyze the heat transfer features. We consider the hexagonal cross-section in our analysis since it has a roundish shape that offers less resistance to fluid flow than the triangular and square designs. Additionally, the hexagonal array can be packed tightly without leaving spaces in between, such as in packing circular tubes. However, having inactive channels within the hexagonal bundle is one of the main challenges which would diminish the thermal performance of counterflow heat exchanger. Therefore, we will consider the hybrid packing of various cross sections. The proposed design is applicable to enhancement of the thermal performance of heat exchangers in general.