Thermal and flow characteristics of a single-row circular-finned tube heat exchanger under elevated free-stream turbulence

Highlights: • The thermal performance of a single-row heat exchanger was investigated. • Grid generated turbulence (GGT) was experimentally characterized. • GGT increased heat transfer in the single-row heat exchanger. • Flow visualizations showed vast changes in flow field under elevated free-stream turbulence. - Abstract: The thermal performance of single-row heat exchangers is generally considered to be inferior to multi-row heat exchangers. It is therefore desirable to optimize the former; especially for those cases which cannot accommodate an alternative. In this study, the heat transfer performance of a single-row circular-finned tube heat exchanger was investigated experimentally under elevated disturbance levels. Specifically, grid-generated turbulence (GGT)—the characteristics of which had been measured beforehand with a hot-wire anemometer—was applied to a clean-flow benchmark case and measurements taken at the heat exchanger outlet. It was shown that when the grid is positioned appropriately, a mean enhancement (in global Nusselt number) of up to 11% can be achieved. Flow visualizations revealed the flow structures responsible for the increase in heat transfer.