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Heat Transfer Intensification in U-bend Double Pipe Heat Exchanger using Twisted Tape Inserts

L Sandeep Raj, K Vijaya Kumar Reddy, A Aruna Kumari

Generating a swirl flow in the flow field is widely employed passive heat transfer augmentation or intensification technique. In present work, twisted tapes are inserted into the inner pipe side of Counter flow U-bend Double Pipe Heat Exchanger for creating a swirl flow and thus Enhancing the Heat Transfer. Twisted tapes of different twist ratios (H/D) 5,10,15,20 and strip insert (i.e without any twist) are employed to enhance the Heat Transfer. Turbulent swirl flow with forced convection is considered for experimental study. For different twist ratios, mass flow rate of cold fluid in inner pipe side is varied, by maintaining the constant mass flow rate in the annulus side. Experimental data is validated using available correlations. The results show that, for mass flow rate of 8 LPM the enhancement in Heat Transfer is 55.69% compared with that of plain tube and corresponding Pressure Drop is only 20%.