Numerical Investigation on Performance Improvement in Tube Inserted with Delta Winglets on Discrete Right-Angled Triangular Plates

Amnart Boonloi,Withada Jedsadaratanachai

doi:10.3844/jmssp.2017.62.69

Abstract

Numerical investigations on flow topology and heat transfer behavior in a round tube heat exchanger inserted with Delta Winglets (DW) on Discrete Right-angled Triangular Plates (DRTP) are performed. The influences of DW heights; b/D or BR = 0.05-0.25 and flow directions; DW with V-Downstream (DWVD) and DW with V-Upstream (DWVU), are studied for turbulent flow; Re = 3000-10,000. The finite volume method with SIMPLE algorithm is selected to solve the present problem. The numerical results are presented in terms of flow and heat transfer mechanisms; tangential velocity vector, TKE contour, Nux contour, temperature contour. The heat transfer rate, pressure loss and thermal performance in the test tube are also analyzed in forms of Nusselt number (Nu), friction factor (f) and Thermal Enhancement Factor (TEF), respectively. The results show that the tube inserted with the DW on DRTP can help to improve the heat transfer rate and thermal performance in the heating section due to the DW can generate the vortex flow that disturbs the thermal boundary layer on the tube wall. In range investigates, the maximum heat transfer rate is around 4.5 times above the smooth tube with the TEF around 1.9.

Highlights

The use of the vortex generators or turbulators in heat exchangers helps to improve heat transfer rate and thermal performance due to they can induce the vortex flow that disturbs the thermal boundary layer on the tube wall
The temperature contour in transverse planes for the round tube heat exchanger inserted with the vortex generator is presented as Fig. 3a and 3b for DW with V-Downstream (DWVD) and DW with VUpstream (DWVU), respectively
The thermal performance of the tube heat exchanger inserted with vortex generators is higher than the smooth tube for all cases (TEF > 1)

Summary

Background

The use of the vortex generators or turbulators in heat exchangers helps to improve heat transfer rate and thermal performance due to they can induce the vortex flow that disturbs the thermal boundary layer on the tube wall. The Delta Winglets (DW) are selected to enhance the heat transfer rate and thermal performance in the circular tube heat exchanger. The temperature contour in transverse planes for the round tube heat exchanger inserted with the vortex generator is presented as Fig. 3a and 3b for DWVD and DWVU, respectively. Considering at red contour, the DWVD provides higher intensity of the Nusselt number contour than the DWVU, while the DWVU performs larger area of high heat transfer rate than the DWVD The reason of this may be that the DWVD and DWVU can generate different flow structure. The thermal performance of the tube heat exchanger inserted with vortex generators is higher than the smooth tube for all cases (TEF > 1).

Conclusion

Funding Information