Numerical simulation of modulated heat transfer tube in laminar flow regime

The flow field modulation concept was proposed. A mesh cylinder was suspended in a tube, dividing the tube cross section into an annular region and a core region. The invention is called the modulated heat transfer tube (MHTT). The numerical simulation was performed in laminar flow regime at constant heat flux boundary condition with water as the working fluid. An equal flow area criterion was proposed for the conversion of 3D to 2D mesh pores. The non-uniform grids link micron scale of mesh pores with meter scale of tube. The results show double-peak velocity distribution over tube cross section. The near wall region has larger velocity and velocity gradient, accounting for the heat transfer enhancement mechanism. For any specific Reynolds number, there is a critical length beyond which heat transfer is deteriorated. Therefore, a set of short mesh cylinders was suspended in the tube. The configuration is called the improved modulated heat transfer tube (IMHTT). It is shown that the IMHTT ensures significant heat transfer enhancement over the whole tube length. This study provides a new enhancement mechanism and tube configuration for heat transfer, having a wide engineering application potential.