Thermo-Hydraulic Performance of Spring Tape Inserts in a Circular Channel in Transitional Flow Regime

Abstract

In this work, forced convection experiments were carried out to investigate the variation of heat transfer and pressure drop inside a uniformly heated circular duct fitted with full-length spring tape inserts of varying spring ratios in a transition flow regime. Air was used as the working fluid medium, and experiments were conducted for three constant heat fluxes of 2, 3, and 4 kW-m⁻² with Reynolds numbers varied from 502 to 10936 to cover all three flow regimes. For a plain channel heated with 2 kW/m² of heat flux, the transition begins at a Reynolds number of 2897 and terminates at a Reynolds number of 3783 which brings the transition Reynolds number width of 886. For the same heat flux, a channel with spring tape having a spring ratio of 3, the transition begins at Reynolds number 661 and ends at 1734 while for the case of spring ratio 5, the transition begins at 1305 and ends at 2226. For constant heat flux conditions, a decrease in the spring ratio results in the early onset of transition and which in turn increased the transition length. Predictive Nusselt number and friction factor correlations for different flow regimes have also been presented.

Disclosure statement

No conflict of interest has been reported by the authors.

Additional information

Funding

The authors gratefully acknowledge the international cooperation division and India-South Africa Bilateral Cooperation Scheme (DST/INT/South Africa/P-08/2021) for the financial support and authors would also like to gratefully acknowledge Birla Institute of Technology and Science, Pilani, Pilani Campus for an additional competitive research grant (ACRG).

Notes on contributors

Devendra Kumar Vishwakarma

Devendra Kumar Vishwakarma is a Ph.D. Research Scholar at the Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani, Rajasthan, India. His research interest includes experimental and numerical heat transfer and pressure drop in laminar, transition, and turbulent flow regimes.

Manoj Kumar Soni

Manoj Kumar Soni is working as an Associate Professor in Mechanical Engineering Department of Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India. He is the coordinator of Center for Renewable Energy and Environmental Development of BITS and also the coordinator of various collaborative Work Integrated Learning Programs of BITS. His research area includes solar energy systems, photovoltaic cells, thermal energy storage systems, energy and exergy analysis of thermal systems, and renewable energy.

Varun Goel

Varun Goel is working as an Associate Professor in Department of Mechanical Engineering, National Institute of Technology, Hamirpur, India. His research area includes solar energy systems, thermal energy storage systems, energy and exergy analysis of thermal systems, and renewable energy.

Suvanjan Bhattacharyya

Suvanjan Bhattacharyya is working as an Assistant Professor in the Department of Mechanical Engineering of Birla Institute of Technology and Science Pilani, Rajasthan, India. He completed his post-doctoral research in the Department of Mechanical and Aeronautical Engineering at the University of Pretoria, South Africa. His research interest lies in CFD in fluid flow and heat transfer, specializing in laminar, turbulent, steady, unsteady separated flows and convective heat transfer, and experimental heat transfer enhancement.