Enhancement of convective heat transfer for high viscous fluid flows

The subject of heat transfer enhancement is a research topic involving considerable attention among the heat transfer research areas. The main target of the enhancement studies, in general, is to improve convection heat transfer coefficient with a possible low pumping power. Heat transfer enhancement studies are usually applied when low convection coefficient case exists. In the practical case, the high viscous fluid flows usually occur in laminar flow regime. Use of such fluids usually requires heat transfer enhancement techniques. In the performed study, the effect of periodically placed wall-attached and wall-detached obstacles perpendicular to the flow axis on heat transfer and frictional loss were numerically investigated. For pipe flow momentum and energy equations were discretized by means of the finite control volume method and were solved by the SIMPLE algorithm via a FORTRAN based computer program. The obtained results show that the enhancement practices work better for the higher viscous fluids. For the attached cases, occurrence of the enhancement is obtained after a certain pitch of obstacle; for the detached case the enhancement is obtained for all the pitches. It is concluded that the hydrodynamic mechanism contributed to heat transfer enhancement are different for the attached and the detached cases.