Enhancement of thermo-hydraulic performance in finned tube heat exchangers with new dimple turbulators

A three-dimensional numerical simulation study was carried out to investigate the effects of five kinds of novelconcave dimple turbulators (CDTs), namely – elliptical dimple (ED), conical frustum dimple (CFD), trapezoidal prismdimple (TPD), leeward triangular dimple (LwTD) and upward triangular dimple (UwTD) on the thermo-hydraulicperformance enhancement in a compact plate fin-and-elliptical tube (PFET) heat exchanger. The computational resultsare analyzed by considering the performance evaluation criterion for the PFET heat exchangers with different types ofCDT shapes.A parametric investigation on the CDTs indicated that the UwTD vortex turbulators give better thermohydraulicperformance under the present conditions. The numerical simulation results illustrated different secondaryflow vortex structures and heat transfer characteristics of the CDTs with various shapes, which disclosed the influentialmechanisms of differently shaped dimple turbulators on the heat transfer augmentation in PFET heat exchangers.

Keywords:

Finned-elliptical tube heat exchanger , Dimple turbulators , Thermo-hydraulic performance