Experimental Study On Design And Affect Factors Of High Efficiency Anti-gravity Flat Plate Heat Pipe

In recent years,with the rapid development of electronic technology,electronic devices get highly improvements to work under high-frequency and high-speed conditions.However,the miniaturization and integration of the microelectronic chip lead to a sharp increase of the heat dissipation in the unit volume,and the heat dissipation of the chip is becoming more and more serious.Due to the high heat transfer performance,the flat plate heat pipe(FPHP)has become the focus of research and development in the field of microelectronics cooling,which has good temperature uniformity,no noise,simple structure and no additional power consumption,etc.In this paper,an efficient antigravity FPHP radiator is designed,and an experimental test platform is set up to investigate the FPHP systematically.The details of the work are as follows:(1)In this paper,a large vapor chamber anti-gravity FPHP for laptop cooling is proposed.And the structure of eight symmetrical arrangement strip pillars consisting of special return passage inside the FPHP is designed.The production process of the FPHP is introduced in detail,including selections and arrangements of wicks,selections of working medium and other main steps.(2)According to the design requirements,two kinds of FPHP with different wicks(copper net wicks and gauze wicks)are processed.The heat transfer performances of the two different FPHP are investigated under the condition of different filling rates and different heating power when the heat source is located at the geometric center of the FPHP experimentally,including the influence on the steady state temperature distribution,the temperature standard deviation,the maximum temperature difference,the thermal resistance and the starting characteristics.The best filling rates of the two different FPHP are obtained by experiments,and the results show that the integrated heat transfer performance of the FPHP with gauze net structure is better than that with the copper net structure.For the FPHP with gauze net structure,the best filling rate is 45%.And under the condition of best filling rate,the temperature standard deviations are 1.2?~1.7?,the maximum temperature differences are 6.3?~8.2?,and the thermal resistances are 0.065K/W~0.19K/W,which can meet the cooling requirement of the laptop.However,for the FPHP with copper net structure,the best filling rate is 40%,and the temperature standard deviations are 3.4?~5.6?,the maximum temperature differences are 9.6 ? ~13.1 ?,the thermal resistances are 0.15K/W~0.33K/W,which cannot meet the cooling requirement of the laptop.And also the starting time of the FPHP with gauze structure is 2000 S,which is better than that with the copper net structure,which is 2600 S.(3)Further experimental studies of the FPHP with gauze net structure are conducted,the influence of the standard deviation,the maximum temperature difference and the thermal resistance on the FPHP with gauze net structure under different filling rates(35%,45%,and 55%)and different heat source positions are analyzed.The results show that the standard deviation,the maximum temperature difference and the thermal resistance at the best filling rate 45% are lower than those of other filling rates,and the standard deviations are 1.2?~3?,the maximum temperature differences are 6.3?~9.6?,the thermal resistances are 0.065K/W~0.3K/W,which can meet the cooling requirement of the laptop.(4)The effective heat transfer length of the FPHP with gauze structure is analyzed theoretically and experimentally.The results show that when the heat source is arranged in the geometric center of the FPHP,the effective heat transfer length is the smallest,which is 0.094 m,and the best heat transfer performance of the FPHP is achieved.