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(No. 5/6) of cooling jacket and the mid of water tank (No. 8) to measure their related average temperature; there were still four more thermal couples applied to measure the temperatures at the vapour (No. 9, 11) and liquid (No. 10, 12) transportation lines; all these thermocouples were further connected to a data logger to record the temperature signals at each testing interval. A control box is provided to adjust the power output of the heating belt, which is considered a thermal load.

A series of laboratory steady-state tests were carried out and the results of the tests were used to evaluate the thermal performance of the proposed GALHP. The testing conditions are displayed in Table 3. During all the sets of tests, the surrounding air temperature and speed were maintained at 20 2°C and 0.01 m/s, respectively. Under initial test conditions, one parameter is changed and the other parameter remains fixed, enabling the development of a correlation between the heat pipe's heat output and associated operating parameters. Once the steady-state conditions have been achieved, the test period is successive 10 h period. The measurement data will be recorded at 5-s interval and logged into the computer system using the DT500 data logger to enable the follow-up analyses to be undertaken.

6. Computer model validation using the experimental results

Table 4 provides the comparison between the testing and the simulation results under all selected testing conditions. The mean correlation coefficient (CR) was found no less than 0.8346 and the root mean square percentage deviation (E) was below 18.18%. This indicated that the developed simulation model could predict the thermal performance at a reasonable accuracy. The differences resolved above may be caused by theoretical and/or inaccurate measurements. From the theoretical side, some simplified assumptions and empirical equations were involved; from the experimental side, a few of the uncertainties addressed above may be the potential reasons for the deviation. Based on these considerations, the errors may be attributed to the theoretical inaccuracies and it would be better for the simulation model to be refined to further improve its accuracy in making predictions based on the

This chapter reported the study of a novel liquid-vapour separator-incorporated gravity-assisted loop heat pipe (GALHP), which was designed, constructed, and tested. A parallel comparison between simulation and experimental results was

Under the specified operational conditions, the start-up timing of the proposed GALHP was 410 s. The overall thermal resistance was 0.11°C/W, indicating that it has small heat transfer resistance owing to its unique structure that led to the even liquid film distribution and thus reduced flow resistance. The actual effective thermal conductivity was 29,968 W/°C m, indicating that it achieved significant improvement in terms of heat transfer. All of these data provide evidence that the proposed GALHP is a super-performance heat transfer device that can be widely used in gravity-assisted heat transfer operations to achieve significant thermal

management in a variety of practical applications.

5.2 Experimental process

Recent Advances in Heat Pipes

experimental results.

7. Conclusion

made.

60

Xudong Zhao<sup>1</sup> \*, Chuangbin Weng<sup>2</sup> , Xingxing Zhang<sup>3</sup> , Zhangyuan Wang<sup>2</sup> and Xinru Wang<sup>4</sup>

1 School of Engineering, University of Hull, UK

2 School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, China

3 Department of Energy, Forest and Built Environments, Dalarna University, Falun, Sweden

4 Department of Architecture and Built Environment, University of Nottingham, Ningbo, China

\*Address all correspondence to: xudong.zhao@hull.ac.uk

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
