Heat transfer enhancement of heat exchanger tube with multiple square perforated twisted tape inserts: Experimental investigation and correlation development

•We had experimental investigated multiple square perforated tape inserts tube.•Significant enhancement was found in thermal performance as compared to plain tube.•Correlation were developed for Nusselt number, friction factor and thermal hydraulic performance.•Correlation can predict the Nusselt number, friction factor and thermal hydraulic performance with in ±10.5% deviation.

The present study examines the augmentation in heat transfer and friction in a flow through heat exchanger tube with multiple square perforated twisted tape inserts. The experimental outcomes pertaining to Reynolds number (Ren) from 5000 to 27000, perforation width ratio (a/WT) from 0.083-0.333 and twist ratio (TL/WT) from 2.0-3.5 have been presented and discussed. Multiple square perforated twist tape brought out considerable enhancement in heat transfer rates over without square perforated multiple twisted tape and plain tube. The maximum enhancement is observed at a a/WT of 0.250 and TL/WT of 2.5. Correlations of Nusselt number, friction factor and thermal hydraulic performance are established in term of Reynolds number and geometrical parameter of twisted tape which can be used to predict the values of Nusselt number, friction factor and thermal hydraulic performance with considerably good accuracy.

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