Effect of twisted-tape inserts and nanofluid on flow field and heat transfer characteristics in a tube

摘要

In the present study, the flow and heat transfer of CuO-water nanofluid in different solid concentrations (1-4 vol %) in a tube have been simulated by using the single- and two-phase (mixture) models. The simulations have been conducted under the turbulent flow regime in different Reynolds numbers ranging from 3000 to 36,000. The effects of using CuO-water nanofluid on the Nusselt number, friction factor, and performance evaluation criterion have been investigated. It is found that employing the two-phase mixture model leads to having closer results in reality compared to the single-phase model. The results revealed that the maximum performance efficiency coefficient in the tube with one twisted tape is 2.18 (for the two-phase model, Re = 36,000 and φ = 4%), while for a tube with two twisted tapes under the same conditions, it is 2.04. Thus, the use of one twisted tape is more favorable from the thermal-fluid dynamics viewpoint.