PERFORMANCE EVALUATION OF TUBE-IN-TUBE HEAT EXCHANGERS WITH HEAT TRANSFER ENHANCEMENT IN THE ANNULUS

Abstract

Different techniques as angled spiraling tape inserts, a round tube in side a twisted square tube and spiraled tube inside the annulus have been used to enhance heat transfer in the annulus of tube-in-tube heat exchangers. The heat transfer enhancement in the shell can be supplemented by heat transfer augmentation in tubes using twisted tape inserts or micro-finned tubes. The effect of the thermal resistance of the condensing refrigerant could also be taken into consideration. To assess the benefit of using these techniques extended performance evaluation criteria have been implemented at different constraints. The decrease of the entropy generation can be combined with the relative increase of the heat transfer rate or the relative reduction of the heat transferarea to find out the geometrical parameters of the tubes for optimal thermodynamics performance. The results show that in most of the cases considered, the angled spiraling tube insert technique is the most efficient.

Keywords

Dates

  • Submission Date2004-12-02
  • Revision Date2005-02-04
  • Acceptance Date2006-02-13

References

  1. Bergles, A.E., Techniques to Augment Heat Transfer, in: Handbook of Heat Transfer Application, McGraw-Hill: New York, 3-1 (Chapter 3), 1985, pp.3-80
  2. Bergles, A.E., Some Perspectives on Enhanced Heat Transfer Second Generation Heat Transfer Technology, ASME Journal of Heat Transfer, 110 (1988), pp.1082-1096
  3. Bergles, A.E., Heat Transfer Enhancement - the Encouragement and Accommodation of High Heat Fluxes, ASME Journal of Heat Transfer, 119 (1997), pp.8-19
  4. Van der Vyver, S., Meyer, J.P., Heat Transfer Augmentation in the Annulus of a Heat Exchanger Consisting of a Round Tube Inside a Twisted Square Tube, R&D Journal, 13 (1997), 3, pp.77-82
  5. Herman, H. and Meyer, J.P., Heat Transfer Augmentation of a Spiralled Tube Inside the Annulus of a Tube-in-Tube Heat Exchanger, R&D Journal, 14 (1998), 3, pp.43-48
  6. Coetzee, H., Heat Transfer and Pressure Drop Characteristics of Angled Spilling Tape Inserts in a Heat Exchanger Annulus, MSc thesis, Rand Afrikaans University, Johannesburg, South Africa, 2001
  7. Meyer, J.P. and Coetzee, H., Tube-in-Tube Heat Exchanger with Enhanced Heat Transfer, Patent no.99/5561 (1999), South Africa
  8. Marner, W.J., Bergles, A.E. and Chenoweth, J.M., On the presentation of performance data for enhanced tubes used in shell-in-tube heat exchangers, ASME Journal of Heat Transfer, 105 (1983), pp.358-365
  9. Webb, R.L., Performance Evaluation Criteria for Use of Enhanced Heat Transfer Surfaces in Heat Exchanger Design, International Journal of Heat and Mass Transfer, 24 (1981), pp.715-726
  10. Zimparov, V.D., Extended Performance Evaluation Criteria for Enhanced Heat Transfer Surfaces: Heat Transfer through Ducts with Constant Wall Temperature, International Journal of Heat and Mass Transfer, 43 (2000), 17, pp.3137-3155
  11. Thome, J. R., High Performance Augmentations for Refrigeration System Evaporators and Condensers, Journal Enhanced Heat Transfer, 1 (1994), 3, pp.275-285
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