Skip to main content

Flow patterns and heat-transfer characteristics of a top heat mode closed-loop oscillating heat pipe with check valves (THMCLOHP/CV)

Abstract

The aim of this research was to investigate the flow patterns and heat transfer of a top heat mode closed-loop oscillating heat pipe with check valves (THMCLOHP/CV). In this study, the heat pipe was made of a high-quality glass capillary tube with an inner diameter of 2.4 mm bent into 10 meandering turns. The number of check valves was 2 and the tube was filled with R141b at a filling ratio of 50% of internal volume of the tube. The combined lengths of the evaporator, adiabatic and condenser sections were equal to 50 mm. The pipe was operated at the top heat mode, and the angles of inclination were 20°, 40°, 60°, 80°, and 90°. The heat applied at the evaporator section was controlled at 85°Cto 105°C, and 125°C. The results show that in the evaporator section, bubbles are produced and grow as a result of the continuous nucleate boiling. They coalesced and their volume expanded. Similarly, in the condenser section the vapor plug condensate caused the bubbles to collapse and accumulate as a liquid mass at the lower section of the U-bend tube. A new slug then developed and the bubbles coalesced in an upward flow. Heat flux increased when the evaporator temperature and inclination angle increased causing the average length of the vapor plug to decrease and the average velocity of vapor plug to increase. The maximum heat flux occurred at an evaporator temperature of 125°C and an inclination angle of minus 90°.

This is a preview of subscription content, access via your institution.

References

  1. 1.

    Akachi, H., Polasek, F., and Stulc, P., Pulsating Heat Pipe, Proc. 5th Int. Heat Pipe Symp., Australia, 1996, pp. 208–217.

  2. 2.

    Gi, K., Sato, F., and Maesawa, S., Flow Visualization Experimental on Oscillating Heat Pipe, Proc. 11th Int. Heat Pipe Conf., Musashinoshi, Tokyo, Japan, 1999, pp. 149–153.

  3. 3.

    Miyazaki, Y., Polasek, S., and Akachi, H., OscillatingHeat Pipe with Check Valves, Proc. 6th Int. Heat Pipe Symp., Chiang Mai, Thailand, 2000, pp. 389–393.

  4. 4.

    Pitpatpaiboon, N., Rittidech, S., Sukna, P., and Suddee, T., Effect of Inclination Angle Working Fluid and Number of Check Valves on the Heat Transfer Characteristics of a Closed-Loop Oscillating Heat Pipe with Check Valves, Proc. 1st Int. Sem. on Heat Pipe and Recovery Systems, Malaysia, 2004, pp. 58–61.

  5. 5.

    Xu, J.L., Li, Y.X., and Wong, T.N., High Speed Flow Visualization of a Closed Loop Pulsating Heat Pipe, Int. J. Heat Mass Transfer, 2005, vol. 48, no. 16, pp. 3338–3351.

    Article  Google Scholar 

  6. 6.

    Tong, B.Y., Wong, T.N., and Ooi, K.T., Closed-Loop Pulsating Heat Pipe, Appl. Therm. Engin., 2001, vol. 21, pp. 1845–1862.

    Article  Google Scholar 

  7. 7.

    Kim, J.-S., Bui, N.H., Kim, J.-W., Kim, J.-H., and Jung, H.-S., Flow Visualization of Oscillation Characteristics of Liquid and Vapor Flow in the Oscillating Capillary Tube Heat Pipe, KSME Int. J., 2003, vol. 17, no. 10, pp. 1507–1519.

    Google Scholar 

  8. 8.

    Rittidech, S., Meena, P., and Terdtoon, P., Effect of Evaporator Lengths and Ratio of Check Valves to Number of Turns on Internal Flow Patterns of a Closed-Loop Oscillating Heat-Pipe with Check Valves, Am. J. Appl. Sci., 2008, vol. 5, no. 3, pp. 184–188.

    Article  Google Scholar 

  9. 9.

    Bhuwakietkumjohn, N. and Rittidech, S., Internal Flow Patterns on Heat-Transfer Characteristic of a Closed-Looped Oscillating Heat-Pipe with Check Valves Using Ethanol and Ethanol Mixed Silver Nano, Exp. Therm. Fluid Sci., 2010, vol. 34, pp. 1000–1007.

    Article  Google Scholar 

  10. 10.

    Maezawa, S., Gi, K.Y., Minamisawa, A., and Akachi, H., Thermal Performance of Capillary Tube Thermosyphon, Proc. Ninth Int. Heat-Pipe Conf., USA, 1996, pp. 791–795.

  11. 11.

    Sampan, R., Heat Pipe Technology (Thai Edition), Mahasarakham Univ., Thailand, 2010, p. 77.

    Google Scholar 

  12. 12.

    Hsu, Y.Y., On the Size Range of Active Nucleation Cavities on a Heating Surface, Trans. ASME J. Heat Transfer, 1962, vol. 84, pp. 207–216.

    Article  Google Scholar 

  13. 13.

    Ma, H.B., Hanlon, M.A., and Chen, C.L., An Investigation of Oscillating Motions in a Miniature Pulsating Heat Pipe, Microfluidics Nanofluidics, 2006, vol. 2, pp. 171–179.

    Article  Google Scholar 

  14. 14.

    Dobson, R.T., Theoretical and Experimental Modeling of an Open Oscillatory Heat Pipe Including Gravity, Int. J. Therm. Sci., 2004, vol. 43, pp. 113–119.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to S. Rittidech.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Thongdaeng, S., Rittidech, S. & Bubphachot, B. Flow patterns and heat-transfer characteristics of a top heat mode closed-loop oscillating heat pipe with check valves (THMCLOHP/CV). J. Engin. Thermophys. 21, 235–247 (2012). https://doi.org/10.1134/S1810232812040029

Download citation

Keywords

  • Inclination Angle
  • Heat Pipe
  • Vapor Bubble
  • Check Valve
  • Engineer THERMOPHYSICS