Abstract

Energy is a major area of concern for many industrial and engineering applications. For the development of energy efficient heat exchangers, heat transfer enhancement by passive inserts have growing research potential. The present study gives the numerical and experimental analysis of twisted tape insert in a circular tube for the range of Reynolds number between 5000 to 15000 with heat flux variation from 500W/m2 to 1.5 kW/m2 with air as working medium. A circular tube of 52.5 mm internal diameter, 60 mm outer diameter and 1000 mm length is used as test section with uniform heat flux. Twisted tape used is of Aluminum material having a pitch of 100 mm. Outside surface temperatures are measured at different locations on test section. Two ‘T’ type thermocouples are used to measure air temperature at inlet and outlet of test section. From numerical and experimental analysis it is observed that the Nusselt number increases for twisted tape as compared to smooth bare tube by 2.2–3.1 times. Again the Nusselt numbers obtained for smooth tube is compared with Dittus-Boelter and Gnielinski correlation and it is observed that the error is within acceptable limit of 10% variation. An error of 10% variation is observed in friction factor obtained by experimental analysis and Blasius and Petukov correlations.

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