# INVESTIGATION AND PREDICTATION OF OPTIMUM MEANDERING TURN NUMBER OF VERTICAL AND HORIZONTAL CLOSED-LOOP PULSATING HEAT PIPES

## Main Article Content

## Abstract

The objectives of this study are to experimentally investigate the effect of meandering turn numbers on thermal performance and to predict the optimum meandering turn number of vertical and horizontal closed-loop pulsating heat pipes (CLPHP). The CLPHPs were made from a copper capillary tube with internal diameter of 2.0 mm. The CLPHPs were bent into undulating tubes with various meandering turn numbers, such as 5, 7, 10, 16, and 30. Each set of the CLPHPs had different evaporator section lengths of 50 mm and 150 mm. Heat input was supplied to the CLPHP by allowing the flow of distilled water as the heating medium through the evaporator section. The adiabatic section temperature was constantly controlled at 50°C. It could be concluded that the optimum meandering turn number of vertical CLPHPs with an evaporator section length of 50 mm is 10 for both R123 and water, and the optimum meandering turn numbers of vertical CLPHPs with an evaporator section length of 150 mm are 5 and 10, respectively, for R123 and water. However, the optimum meandering turn number of the horizontal CLPHP could not be found since the heat flux directly varies with the turn number. In addition, the correlation to predict the optimum meandering turn number of the vertical CLPHP was successfully established.

## Article Details

**Thermal Science**, [S.l.], mar. 2017. ISSN 2334-7163. Available at: <http://thermal-science.tech/journal/index.php/thsci/article/view/2183>. Date accessed: 23 june 2017. doi: https://doi.org/10.2298/TSCI150707161K.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Authors retain copyright of the published article and have the right to use the article in the ways permitted to third parties under the - Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) licence. Full bibliographic information (authors, article title, journal title, volume, issue, pages) about the original publication must be provided and a link must be made to the article's DOI.

The authors and third parties who wish use the article in a way not covered by the the -Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) licence must obtain a written consent of the publisher. This license allows others to download the paper and share it with others as long as they credit the journal, but they cannot change it in any way or use it commercially.

Authors grant to the publisher the right to publish the article, to be cited as its original publisher in case of reuse, and to distribute it in all forms and media.

Accepted 2017-03-13

Published 2017-03-13

## References

[2] Maezawa, S. et al., Thermal Performance of Capillary Tube Thermosyphon, Proceedings, 9th Intl. Heat Pipe Conf., Albuquerque, USA, 1995, pp. 791–795.

[3] Soponpongpipat, N. et al., Investigation of the Startup Condition of a Closed Loop Oscillating Heat Pipe, Heat Transfer Eng., 30 (2009), 8, pp. 626–642.

[4] Kammuang-lue, N. et al., Correlation to Predict the Maximum Heat Flux of a Vertical Closed- Loop Pulsating Heat Pipe, Heat Transfer Eng., 30 (2009), 12, pp. 961–972.

[5] Panyoyai, N. et al., Effects of Aspect Ratios and Number of Meandering Turns on Performance Limit of an Inclined Closed-Loop Oscillating Heat Pipe, Energy Res. J., 1 (2010), 2, pp. 91–95.

[6] Kammuang-lue, N. et al., Establishment, Verification and Application of a Correlation to Predict the Maximum Heat Flux of a Horizontal Closed-Loop Pulsating Heat Pipe, Energy Res. J., 1 (2010), 2, pp. 96–103.

[7] Panyoyai, N. et al., Effect of Inclination Angles on Internal Flow Pattern of Closed-Loop Oscillating Heat Pipe at Maximum Heat Flux State, Proceedings, 3rd Intl. Conf. on Science, Technology and Innovation for Sustainable Well-Being, Danang, Viet Nam, 2011, pp. 57–62.

[8] Charoensawan, P. et al., Effect of Evaporator Section Lengths, Number of Turns and Working Fluid on Internal Flow Patterns of a Vertical Closed-Loop Oscillating Heat Pipe, Proceedings, 7th Intl. Heat Pipe Symp., Jeju, South Korea, 2003, pp. 360–367.

[9] Charoensawan, P., Terdtoon, P., Thermal Performance of Horizontal Closed-Loop Oscillating Heat Pipe, Appl. Therm. Eng., 28 (2008), 5-6, pp. 460–466.

[10] Charoensawan, P. et al., Closed Loop Pulsating Heat Pipes - Part A: Parametric Experimental Investigations, Appl. Therm. Eng., 23 (2003), 16, pp. 2009–2020.

[11] Charoensawan, P. et al., Effect of Inclination Angles, Filling Ratios and Total Lengths on Heat Transfer Characteristics of a Closed-Loop Oscillating Heat Pipe, Proceedings, 6th Intl. Heat Pipe Symp., Chiang Mai, Thailand, 2000, pp. 421–430.

[12] Khandekar, S. et al., Understanding Operational Regimes of Closed Loop Pulsating Heat Pipes: An Experimental Study, Appl. Therm. Eng., 23 (2003), 6, pp. 707–719.

[13] Dobson, R. T., Graf, G., Thermal Characterisation of an Ammonia-Charged Pulsating Heat Pipe, Proceedings, 7th Intl. Heat Pipe Symp., Jeju, South Korea, 2003, pp. 325–330.

[14] Dmitrin, V. I., Maidanik, Yu. F., Experimental Investigations of a Closed-Loop Oscillating Heat Pipe, High Temp., 45 (2007), 5, pp. 703–707.

[15] Khandekar, S. et al., Closed Loop Pulsating Heat Pipes - Part B: Visualization and Semi- Empirical Modeling, Appl. Therm. Eng., 23 (2003), 16, pp. 2021–2033.

[16] Soponpongpipat, N. et al., Prediction Model of Average Heat Transfer Capacity of Closed-Loop Oscillating Heat Pipe at Normal Operation, Proceedings, 8th Intl. Heat Pipe Symp., Kumamoto, Japan, 2006, pp. 154–159.

[17] Charoensawan, P., Terdtoon, P., Thermal Performance Correlation of Horizontal Closed-Loop Oscillating Heat Pipes, Proceedings, 9th Electronics Packaging Technology Conf., Singapore, 2007, pp. 906–909.

[18] Yeunyongkul, P. et al., Experimental Investigation of the Closed Loop Oscillating Heat Pipe Condenser for Vapor Compression Refrigeration, J. Appl. Sci. Eng., 15 (2012), 2, pp. 117–122.

[19] Kammuang-lue, N. et al., Effect of Working Fluids on Thermal Effectiveness of Closed-Loop Pulsating Heat Pipe Applied in Ice Storage System, Proceedings, 8th Intl. Heat Pipe Symp., Kumamoto, Japan, 2006, pp. 323–328.

[20] Kammuang-lue, N. et al., Effect of Inclination Angles on Thermal Effectiveness of a Closed- Loop Pulsating Heat Pipe Applied in Ice Storage System, Proceedings, 7th Eco-Energy and Materials Science and Engineering Symp., Chiang Mai, Thailand, 2009, pp. 270–274.

[21] Zhang, Y., Faghri, A., Advances and Unsolved Issues in Pulsating Heat Pipes, Heat Transfer Eng., 29 (2007), 1, pp. 20–44.

[22] On-ai, K. et al., Effect of Working Fluid Types on Thermal Performance of Vertical Closed- Loop Pulsating Heat Pipe, Proceedings, 5th Intl. Conf. on Science, Technology and Innovation for Sustainable Well-Being, Luang Prabang, Lao PDR, 2013, pp. MME04 1-7.