Assessment of the influence of the length and number of heat pipes on the efficiency of the removal of excess thermal energy from the processor

The results of a study of the influence of the length and number of heat pipes included in the radiator construction on the efficiency of removing excess thermal energy from modern processors are presented. Research was carried out for radiator constructions consisting of a heat sink, a heat pipe and a finned radiator installed on the processor and located in an open environment (air movement occurs without mixing, which is typical for free convection) or in a closed environment (air flows circulate in a closed loop, which is typical for natural convection in a limited space). Numerical modeling was carried out using the Flow Simulation module of the SolidWorks software package. It has been shown that the value of the temperature difference formed at the ends of heat pipes (hereinafter referred to as HP) significantly depends on the natural movement of air flows in an open or closed environment. It has been established that with an increase in the length of the HP from 100 mm to 500 mm, the temperature difference increases both in the case of air flow in an open environment and in a closed environment, in particular, the temperature difference increase at the ends of one HP with a diameter of 6 mm at power 50 W processor will be 29.54 °C (open environment) and 47.14 °C (closed environment); for three HPs – 9.13 °С (open environment) and 16.28 °С (closed environment); for five HPs – 5.24 °С (open environment) and 10.11 °С (closed environment). It has been established that an increase in the number of HPs with a diameter of 6 mm and a length of 500 mm from 1 pc. up to 5 pcs. leads to a decrease in temperature difference, in particular, with a processor power of 50 W, the temperature difference will be 36.17 °C (one HP in an open environment) and 55.59 °C (one HP in a closed environment); 11.04 °С (three HPs in an open environment) and 19.06 °С (three HPs in a closed environment); as well as 6.3 °С (five HPs in an open environment) and 11.56 °С (five HPs in a closed environment). The results obtained can be used to modernize the cooling systems of various technical devices based on processors, as well as to design new high-performance equipment taking into account the use of heat pipes.

1. Nemec P., Čaja A., Malcho M. Mathematical model for heat transfer limitations of heat pipe. Mathematical and Computer Modelling, 2013, vol. 57, iss. 1–2, pp. 126–136. https://doi.org 10.1016/j.mcm.2011.06.047

2. Wang Yu, Denisov O. V., Denisova L. V. Simulation of processor cooling in a nanosatellite using loop heat pipes. Vestnik RUDN. Seriya: Inzhenernye issledovaniya = RUDN Journal of Engineering Research, 2019, vol. 20, no. 3, pp. 211–219 (in Russian). https://doi.org 10.22363/2312-8143-2019-20-3-211-219

3. Piskun G. A., Alexeev V. F., Belikov A. N., Rybakov D. G. Simulation of Thermal Energy Removal from Processors Using Air Coolers. Doklady BGUIR, 2023, vol. 21, no. 4, pp. 54–62 (in Russian). https://doi.org/10.35596/1729-7648-2023-21-4-54-62

4. Piskun G. A., Alexeev V. F., Belikov A. N., Rybakov D. G. Influence of channel orientation in air coolers on the efficiency of heat removal from powerful semiconductor devices. Doklady BGUIR, 2023, vol. 21, no. 5, pp. 33–41 (in Russian). https://doi.org/10.35596/1729-7648-2023-21-5-33-41

5. Sokolov N. Yu., Kulagin V. A., Nesterov D. A. Mathematical modeling and optimization heat pipe systems. Zhurnal Sibirskogo federal’nogo universiteta. Tekhnika i tekhnologii = Journal of Siberian Federal University. Engineering & Technologies, 2021, vol. 14, no. 7, pp. 860–879 (in Russian). https://doi.org/10.17516/1999-494X-0352

6. Abiev R. S., Kumar R. Mathematical Model of Heat Transfer in a Microchannel Heat Pipe with Circulation of a TwoPhase Medium. Izvestiya Sankt-Peterburgskogo gosudarstvennogo tekhnologicheskogo instituta (tekhnicheskogo universiteta) = Bulletin of the Saint Petersburg State Institute of Technology (Technical University), 2020, iss. 55 (81), pp. 61–67 (in Russian). https://doi.org/10.36807/1998-9849-2020-55-81-62-67

7. Khalid S. U., Babar H., Ali H. M., Janjua M. M., Ali M. A. Heat pipes: progress in thermal performance enhancement for microelectronics. Journal of Thermal Analysis and Calorimetry, 2020, vol. 143, pp. 2227–2243. https://doi.org/10.1007/s10973-020-09820-7

8. Faghri A. Heat pipes: review, opportunities and challenges. Frontiers in Heat Pipes, 2014, vol. 5, pp. 123–161. https://doi.org/10.5098/fhp.5.1

9. Heat Pipe Design Guide. CELSIA: Making Hot Technology Cooler. Available at: https://celsiainc.com/heat-sink-blog/heat-pipe-design-guide (accessed 14 November 2023).

10. Heat Pipes: Effective, Reliable Cooling Solutions. BOYD. Available at: https://www.boydcorp.com/thermal/twophase-cooling/heat-pipe-assemblies.html (accessed 14 November 2023).

11. Vasiliev L. L. Heat pipes in modern heat exchangers. Applied Thermal Engineering. 2005, vol. 25, no. 1, pp. 1–19. https://doi.org/10.1016/j.applthermaleng.2003.12.004

12. Luks A. L., Matveev A. G. Analysis of the main calculated and experimental thermophysical characteristics of ammonia heat pipes with increased thermal conductivity from aluminum alloys. Vestnik Samarskogo universiteta. Estestvennonauchnaya seriya = Vestnik of Samara University. Natural Science Series, 2008, no. 3 (62), pp. 331–357 (in Russian).

13. Sokolov N. Yu., Kulagin V. A. Numerical and physical modeling of the operation of a heat pipe system for heat removal from radioelectronic equipment for various purposes. Informatsionnye i matematicheskie tekhnologii v nauke i upravlenii = Information and Mathematical Technologies in Science and Management, 2022, vol. 4, no. 28, pp. 50– 69 (in Russian). https://doi.org/10.38028/ESI.2022.28.4.004

14. Höhne T. CFD simulation of a heat pipe using the homogeneous model. International Journal of Thermofluids, 2022, vol. 15, pp. 24–31. https://doi.org/10.1016/j.ijft.2022.100163

15. SOLIDWORKS Flow Simulation Electronics Cooling. Part 3: Heat Pipes. 2019. Available at: https://www.cati.com/blog/solidworks-flow-simulation-electronics-cooling-part-3-heat-pipes (accessed 14 November 2023).