Hostname: page-component-7dd5485656-gs9qr Total loading time: 0 Render date: 2025-10-30T00:44:12.030Z Has data issue: false hasContentIssue false
  • English
  • Français

An Experimental Study of Falling Film Evaporation on Horizontal Tubes Using R-134a

Published online by Cambridge University Press:  08 May 2012

L.-H. Chien  and
R.-H. Chen
L.-H. Chien*
Affiliation:
Department of Energy and Refrigerating Air-Conditioning EngineeringNational Taipei University of Technology, Taipei, Taiwan 10608, R.O.C.
R.-H. Chen
Affiliation:
Department of Energy and Refrigerating Air-Conditioning EngineeringNational Taipei University of Technology, Taipei, Taiwan 10608, R.O.C.
*
*Corresponding author (lhchien@ntut.edu.tw)
Get access

Abstract

This study investigates evaporation heat transfer performance of refrigerant R-134a falling film on three horizontal copper tubes in a vertical column. Experiments were performed at saturation temperatures of 10 and 26.7°C. The liquid flows through a liquid feeder with a row of circular holes at a rate of 0.0075 ∼ 0.0363kg/ms, while heat fluxes varied from 4.5 to 48.5kW/m2. A smooth tube, a fin tube of 0.4mm fin height, 60FPI (Fins Per Inch), and a new boiling enhanced tube (mesh tube) were tested. The test results show that heat transfer coefficient of the smooth tube increases with increasing heat flux and fluid temperature, and increases slightly with increasing flow rate before dry-out occurs. At low flow rates (less than 0.015kg/ms) or when Ref (≤ 255), the fin tube is in thin film evaporation mode and results in a large heat transfer coefficient. At high flow rates (0.0225, 0.03, and 0.0375kg/ms) the falling film evaporation curves are similar to those in pool boiling. For all tubes, the fluid temperature and the flow rate have only minor influences on heat transfer coefficient before dry-out occurs. The 60 FPI tube and the mesh tube enhance the falling film evaporation heat transfer coefficient 6.3 ∼ 8.29 fold and 1.9 ∼ 5.0 fold, respectively, as compared with the smooth tube. A new correlation of falling film evaporation, accounting for contributions of nucleate boiling and spray convection, is proposed. It predicts h-values of the falling film evaporation data of the smooth surface within ±30%.

Keywords

Falling film evaporationEvaporatorFinDry-out

Information

Type
Articles
Information
Journal of Mechanics , Volume 28 , Issue 2 , June 2012 , pp. 319 - 327
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

REFERENCES

1. Chun, K. R. and Seban, R. A., “Heat Transfer to Evaporating Liquid Films.” Trans. ASME, Journal of Heat Transfer, 93, pp. 391–396 (1971).CrossRefGoogle Scholar
2. Chyu, M. C. and Bergles, A. E., “An Analytical and Experimental Study of Falling-Film Evaporation on a Horizontal Tube,” Journal of Heat Transfer, 109, pp. 983–990 (1987).CrossRefGoogle Scholar
3. Fujita, Y. and Tsutsui, M., “Experimental Investigation of Falling Film Evaporation on Horizontal Tubes,” Heat Transfer-Japanese Research, 27, pp. 609–618 (1998).3.0.CO;2-N>CrossRefGoogle Scholar
4. Fujita, Y., Tsutsui, M. and Zhou, Z-Z., “Evaporation Heat Transfer of Falling Films on Horizontal Tube - Part 1, Analytical Study,” Heat Transfer - Japanese Research, 24, pp. 1–16 (1995).Google Scholar
5. Fujita, Y., Tsutsui, M. and Zhou, Z-Z., “Evaporation Heat Transfer of Falling Films on Horizontal Tube - Part 2, Experimental Study,” Heat Transfer - Japanese Research, 24, pp. 17–31 (1995).Google Scholar
6. Hu, X. and Jacobi, A. M., “The Intertube Falling Film: Part 1-Flow Characteristics, Mode Transitions, and Hysteresis,” Journal of Heat Transfer, 118, pp. 616–625 (1996).CrossRefGoogle Scholar
7. Hu, X. and Jacobi, A. M., “The Intertube Falling Film: Part 2-Mode Effects on Sensible Heat Transfer to a Falling Liquid Film.” Journal of Heat Transfer, 118, pp. 626–633 (1996).CrossRefGoogle Scholar
8. Roques, J. F. and Thome, J. R., “Falling Films on Arrays of Horizontal Tubes with R-134a, Part II: Flow Visualization, Onset of Dryout, and Heat Transfer Predictions.” Heat Transfer Engineering, 28, pp. 415–434 (2007).CrossRefGoogle Scholar
9. Moeykens, S. and Pate, M. B., “Spray Evaporation Heat Transfer Performance of R-134a on Plain Tubes,” Ashrae Transactions, 100, pp. 173–184 (1994).Google Scholar
10. Moeykens, S. and Pate, M. B., “The Effects of Nozzle Height and Orifice Size on Spray Evaporation Heat Transfer Performance for a Low-finned, Triangular-pitch Tube Bundles with R-134a,” Ashrae Transactions, 101, pp. 420–433 (1995).Google Scholar
11. Moeykens, S. and Pate, M. B., “Effect of Lubricant on Spray Evaporation Heat Transfer Performance of R-134a and R-22 in Tube Bundles,” Ashrae Transactions, 102, pp. 410–426 (1996).Google Scholar
12. Moeykens, S. A., Newton, B. J. and Pate, M. B., “Effects of Surface Enhancement, Film-feed Supply Rate, and Bundle Geometry on Spray Evaporation Heat Transfer Performance,” Ashrae Transactions, 101, pp. 408–419 (1995).Google Scholar
13. Moeykens, S. A., Kelly, J. E. and Pate, M. B., “Spray Evaporation Heat Transfer Performance of R-123 in Tube Bundles,” Ashrae Transactions, 102, pp. 259–272 (1996).Google Scholar
14. Chang, T. B. and Chiou, J. S., “Spray Evaporation Heat Transfer of R-141b on a Horizontal Tube Bundle,” International Journal of Heat & Mass Transfer, 42, pp. 1467–1478 (1998).CrossRefGoogle Scholar
15. Liu, Z. H. and Yi, J., “Enhanced Evaporation Heat Transfer of Water and R-11 Falling Film with the Roll-Worked Enhanced Tube Bundle,” Experimental Thermal and Fluid Science, 25, pp. 447–455 (2001).CrossRefGoogle Scholar
16. Chien, L.-H. and Cheng, H.-C., “A Predictive Model of Falling Film Evaporation with Bubble Nucleation on Horizontal Tubes,” International Journal of HVAC&R Research, 12, pp. 69–87 (2006).Google Scholar
17. Chien, L.-H., Wang, S.-M. and Liao, W.-R., “Computational Flow Dynamics of the Refrigerant Distribution in a Spray Type Evaporator,” Advanced Science Letters, 4, pp. 745–749 (2011).CrossRefGoogle Scholar
18. Chien, L.-H. and Huang, H.-L, “An Experimental Study of Boiling Heat Transfer Enhancement on Mesh-on-fin Tubes,” Journal of Enhanced Heat Transfer, 19, pp. 75–86 (2012).CrossRefGoogle Scholar
19. Chien, L.-H. and Lin, H.-T., “An Experimental Study of Falling Film Evaporation on Inclined Plates Using R141b and R134a,” Ashrae Transaction, 113, pp. 211–219 (2007).Google Scholar
20. Chien, L.-H. and Tsai, Y.-L., “An Experimental Study of Pool Boiling and Falling Film Vaporization on Horizontal Tubes in R-245fa,” Applied Thermal Engineering, 31, pp. 4044–4054 (2011).CrossRefGoogle Scholar
21. Cooper, M. G., “Saturation Nucleate Pool Boiling - a Simple Correlation,” International Chemical Engineering Symposium Series, 86, pp. 785–792 (1984).Google Scholar
22. Alhusseini, A. A., Tuzla, K. and Chen, J. C., “Falling Film Evaporation of Single Component Liquids,” International Journal of Heat and Mass Transfer, 41, pp. 1623–1632 (1998).CrossRefGoogle Scholar