Optimisation of heat transfer enhancement devices in a bayonet tube heat exchanger

This paper considers the assessment and analysis of heat transfer enhancement devices which can be considered for a bayonet tube heat exchanger. Due to restraining conditions, such as material selection, manufacturing complexity, etc., simple rib roughened surfaces in the form of rings were used on the air side flow, in the annulus. Analysis of the effect of the rings were studied, starting from cited geometries, using computational fluid dynamics. Validation was carried out using laser diagnostics. For the range of Reynolds numbers (Re_ave=160,000) considered the optimal ring configuration was a ring to annulus height ratio of 0.37 with a pitch to ring height ratio of 10. This provided the optimal heat flux to pressure drop for the given conditions.