Numerical simulation of start-up characteristics and heat transfer performance of ultra-thin heat pipe

doi:10.11949/0438-1157.20230429

Abstract

Abstract:

In this paper, a simplified three-dimensional transient model of ultra-thin heat pipe was proposed to simulate the process of heat pipe from start-up to stable operation. Based on the previous work of the team, the accuracy of the model was verified. Heat pipes with different vapor core thicknesses, types of wicks and bending section geometry were studied by numerical simulation. The influence of different parameters on the vapor flow characteristics, temperature distribution and start-up performance is analyzed. Based on the control theory, the thermal response characteristics of heat pipes with different structures are quantitatively analyzed. The maximum RMSE is only 0.385. The results show that the flow resistance and energy loss of vapor will increase if the vapor core thickness is too small. Different structures of wicks mainly affect the steam flow characteristics through the difference in the width of the steam channel. The smaller the vapor core thickness is, the more easily it is affected by the bending radius and bending angle of the bending section. In addition, if the thickness of the flow channel is less than 0.2 mm, it will also affect the temperature uniformity of the heat pipe and limit the vapor-liquid circulation. The total thermal resistance and start-up time of the heat pipe are mainly affected by the heat load.

Key words: ultra-thin heat pipe, numerical simulation, phase change, heat transfer, start-up performance

摘要：

提出了一种简化的超薄热管三维瞬态模型，模拟热管由启动至稳定运行的过程，基于团队前期工作验证了模型的准确性，通过数值模拟研究了不同流道厚度、吸液芯类型及折弯段几何结构的热管，分析了各参数对蒸汽流动特性、温度分布特性及启动性能的影响，基于控制理论对不同结构热管的热响应特性进行了定量分析，最大均方根误差(RMSE)仅为0.385。研究表明：流道厚度过小将增大蒸汽流动阻力和能量损失，不同结构吸液芯主要通过蒸汽通道宽度差异影响蒸汽流动特性，流道厚度越小越易受折弯段折弯半径和折弯角度的影响。此外，流道厚度小于0.2 mm还将影响热管均温性，使气液循环受限，热管总热阻和启动时间主要受热负荷的影响。

关键词: 超薄热管, 数值模拟, 相变, 传热, 启动性能

CLC Number:

TK 172.4

Fangzhe SHI, Yunhua GAN. Numerical simulation of start-up characteristics and heat transfer performance of ultra-thin heat pipe[J]. CIESC Journal, 2023, 74(7): 2814-2823.

史方哲, 甘云华. 超薄热管启动特性和传热性能数值模拟[J]. 化工学报, 2023, 74(7): 2814-2823.

Figures/Tables 14

Fig.1 Geometric model of ultra-thin heat pipe

Table 1 Structural parameters of heat pipe and heating condensation module

参数	数值
热管长度/mm	115
热管宽度/mm	7.7
热管壁厚/mm	0.2
流道厚度/mm	0.1~0.4
加热铜块尺寸/mm×mm	7.7×15
冷却铜块尺寸/mm×mm	7.7×40
冷却水流量/(L·h^-1)	20

Table 2 Structural parameters of wick

名称	每毫米孔数	线径/mm	宽度/mm	孔隙率	渗透率/m²
NSM	6.02	0.04	2.6	0.801	1.709×10^-10
TSM	6.69	0.04	3.0	0.779	1.273×10^-10
ESM	7.36	0.04	3.4	0.757	9.652×10^-11

Fig.2 Grid independence test

Fig.3 Comparison between simulated and experimental values of heat pipe temperature

Fig.4 Relationship between steam pressure drop and heat load with different channel thickness

Fig.5 Effect of different channel thickness and wick structure on the average steam velocity in the bending section

Fig.6 Influence of bending radius of heat pipe on circulating flow rate and average speed of bending section

Fig.7 Influence of different channel thickness, wick structure and bending angle on maximum steam velocity

Fig.8 Temperature distribution of heat pipe with different channel thickness

Fig.9 Influence of heat load on thermal resistance of heat pipe with different channel thickness

Fig.10 Relationship between start-up time and heating power of heat pipe with different channel thickness

Fig.11 Control theory of heat pipe thermal response and numerical simulation of temperature changes

Table 3 Calculation values of control theory parameter for UTHP startup

传递函数	h_w/mm	T_ct/℃	RMSE	k_ct	t_ct/s
$k c t 1 + t c t S$	0.1	55.895	0.385	4.955	27.002
	0.2	48.160	0.376	4.566	31.579
	0.3	46.882	0.196	4.511	34.567

Table 3 Calculation values of control theory parameter for UTHP startup

传递函数	h_w/mm	T_ct/℃	RMSE	k_ct	t_ct/s
$k c t 1 + t c t S$	0.1	55.895	0.385	4.955	27.002
	0.2	48.160	0.376	4.566	31.579
	0.3	46.882	0.196	4.511	34.567

References 35

1	姚寿广, 马哲树, 罗林, 等. 电子电器设备中高效热管散热技术的研究现状及发展[J]. 华东船舶工业学院学报(自然科学版), 2003, 17(4): 9-12.
	Yao S G, Ma Z S, Luo L, et al. Improvement of heat pipe technique for high heat flux electronics cooling[J]. Journal of East China Shipbuilding Institute (Natural Science Edition), 2003, 17(4): 9-12.
2	辛乃龙. 纯电动汽车锂离子动力电池组热特性分析及仿真研究[D]. 长春: 吉林大学, 2012.
	Xin N L. Thermal characteristic analysis and simulation research of lithium-ion power battery pack for pure electric vehicle[D]. Changchun: Jilin University, 2012.
3	高翔, 凌惠琴, 李明, 等. CPU散热技术的最新研究进展[J]. 上海交通大学学报, 2007, 41(S2): 48-52.
	Gao X, Ling H Q, Li M, et al. Recent advance in cooling techniques for CPU[J]. Journal of Shanghai Jiao Tong University, 2007, 41(S2): 48-52.
4	Lv Y G, Zhang G P, Wang Q W, et al. Management technologies used for high heat flux automobiles and aircraft: a review[J]. Energies, 2022, 15(21): 8316.
5	庄骏, 张红. 热管技术及其工程应用[M]. 北京: 化学工业出版社, 2000.
	Zhuang J, Zhang H. Heat Pipe Technology and Engineering Application[M]. Beijing: Chemical Industry Press, 2000.
6	田晟, 肖佳将. 基于正交层次法的锂离子电池热管散热模组数值模拟分析[J]. 化工学报, 2020, 71(8): 3510-3517.
	Tian S, Xiao J J. Numerical simulation and analysis of lithium-ion battery heat pipe cooling module based on orthogonal analytic hierarchy process[J]. CIESC Journal, 2020, 71(8): 3510-3517.
7	朱玙灯, 付婷, 曾良才, 等. 超薄热管传热性能的数值模拟[J]. 机械制造, 2021, 59(6): 37-42.
	Zhu Y D, Fu T, Zeng L C, et al. Numerical simulation of heat transfer property of ultra-thin heat pipe[J]. Machinery, 2021, 59(6): 37-42.
8	Zhou W J, Li Y, Chen Z S, et al. Design and experimental study on a new heat dissipation method for watch-phones[C]//Wen C, Yan Y. Advances in Heat Transfer and Thermal Engineering. Singapore: Springer, 2021: 621-625.
9	Tang H, Weng C X, Tang Y, et al. Effect of inclination angle on the thermal performance of an ultrathin heat pipe with multi-scale wick structure[J]. International Communications in Heat and Mass Transfer, 2020, 118: 104908.
10	Koito Y. Numerical analyses on heat transfer characteristics of ultra-thin heat pipes: fundamental studies with a three-dimensional thermal-fluid model[J]. Applied Thermal Engineering, 2019, 148: 430-437.
11	唐恒. 丝网吸液芯超薄热管制造及其传热性能研究[D]. 广州: 华南理工大学, 2018.
	Tang H. Study on fabrication and heat transfer performance of ultra-thin heat pipe with copper mesh wick[D]. Guangzhou: South China University of Technology, 2018.
12	汤勇, 孙亚隆, 唐恒, 等. 柔性热管的研究现状与发展趋势[J]. 机械工程学报, 2022, 58(10): 265-279.
	Tang Y, Sun Y L, Tang H, et al. Development status and perspective trend of flexible heat pipe[J]. Journal of Mechanical Engineering, 2022, 58(10): 265-279.
13	陈恭. 气液共面结构超薄均热板设计制造及其性能研究[D]. 广州: 华南理工大学, 2021.
	Chen G. Design, manufacture and performance study of ultra-thin vapor chamber with gas-liquid coplanar structure[D]. Guangzhou: South China University of Technology, 2021.
14	Dai X, Tang Y L, Liu T Q, et al. Experimental investigation on the thermal characteristics of ultra-thin flattened heat pipes with bending angles[J]. Applied Thermal Engineering, 2020, 172: 115150.
15	Murer S, Lybaert P, Gleton L, et al. Experimental and numerical analysis of the transient response of a miniature heat pipe[J]. Applied Thermal Engineering, 2005, 25(16): 2566-2577.
16	Cui Z, Jia L, Wang Z, et al. Thermal performance of an ultra-thin flat heat pipe with striped super-hydrophilic wick structure[J]. Applied Thermal Engineering, 2022, 208: 118249.
17	Kholi F K, Mucci A, Kallath H, et al. Experimental investigation of the effects of inclinations and wicks on the thermal behavior of heat pipes for improved thermal applications[J]. Case Studies in Thermal Engineering, 2021, 26: 100997.
18	Famouri M, Carbajal G, Li C. Transient analysis of heat transfer and fluid flow in a polymer-based micro flat heat pipe with hybrid wicks[J]. International Journal of Heat and Mass Transfer, 2014, 70: 545-555.
19	杨露露, 徐洪波, 王惠惠, 等. 平板微热管阵列的研究现状与进展[J]. 制冷学报, 2020, 41(5): 1-11, 22.
	Yang L L, Xu H B, Wang H H, et al. Research status and progress of flat plate micro heat pipe array[J]. Journal of Refrigeration, 2020, 41(5): 1-11, 22.
20	Chen P Z, Pan Z L. Heat transfer analysis of flat heat pipe with enhanced microchannel shape[J]. IEEE Access, 2021, 9: 120833-120843.
21	Plawsky J L, Fedorov A G, Garimella S V, et al. Nano- and microstructures for thin-film evaporation: a review[J]. Nanoscale and Microscale Thermophysical Engineering, 2014, 18(3): 251-269.
22	Singh S K, Sharma D. Review of pool and flow boiling heat transfer enhancement through surface modification[J]. International Journal of Heat and Mass Transfer, 2021, 181: 122020.
23	Alhuyi Nazari M, Ghasempour R, Ahmadi M H. A review on using nanofluids in heat pipes[J]. Journal of Thermal Analysis and Calorimetry, 2019, 137(6): 1847-1855.
24	Hassan H, Harmand S. Study of the parameters and characteristics of flat heat pipe with nanofluids subjected to periodic heat load on its performance[J]. International Journal of Thermal Sciences, 2015, 97: 126-142.
25	Kasaeian A, Daneshazarian R, Mahian O, et al. Nanofluid flow and heat transfer in porous media: a review of the latest developments[J]. International Journal of Heat and Mass Transfer, 2017, 107: 778-791.
26	Datta A, Sanyal D, Agrawal A, et al. A review of liquid flow and heat transfer in microchannels with emphasis to electronic cooling[J]. Sādhanā, 2019, 44(12): 1-32.
27	甘云华, 黄昭惠, 梁嘉林, 等. 部分压扁热管等效导热模型特性研究[J]. 华南理工大学学报(自然科学版), 2021, 49(10): 123-132.
	Gan Y H, Huang Z H, Liang J L, et al. Research on the characteristics of conduction-based model of partially flattened heat pipe[J]. Journal of South China University of Technology (Natural Science Edition), 2021, 49(10): 123-132.
28	Yu J, Li Y, Xin Z F, et al. Experimental investigation on the thermal characteristics of ultrathin vapour chamber with in-plane bending[J]. Applied Thermal Engineering, 2022, 217: 119175.
29	Zhou W J, Li Y, Chen Z S, et al. Ultra-thin flattened heat pipe with a novel band-shape spiral woven mesh wick for cooling smartphones[J]. International Journal of Heat and Mass Transfer, 2020, 146: 118792.
30	Ahamed M S, Saito Y, Mashiko K, et al. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices[J]. Heat and Mass Transfer, 2017, 53(11): 3241-3247.
31	Jiang L L, Tang Y, Pan M Q. Effects of bending on heat transfer performance of axial micro-grooved heat pipe[J]. Journal of Central South University, 2011, 18(2): 580-586.
32	Ranjan R, Murthy J Y, Garimella S V, et al. A numerical model for transport in flat heat pipes considering wick microstructure effects[J]. International Journal of Heat and Mass Transfer, 2011, 54(1/2/3): 153-168.
33	Xiao B, Faghri A. A three-dimensional thermal-fluid analysis of flat heat pipes[J]. International Journal of Heat and Mass Transfer, 2008, 51(11/12): 3113-3126.
34	Golnaraghi M F, Kuo B C. Automatic Control Systems[M]. 10th ed. New York: McGraw-Hill Education, 2017: 139-171.
35	Ljung L. System identification[M]//Signal Analysis and Prediction. Boston, MA: Birkhäuser Boston, 1998: 163-173.

[1]	Zhanyu YE, He SHAN, Zhenyuan XU. Performance simulation of paper folding-like evaporator for solar evaporation systems [J]. CIESC Journal, 2023, 74(S1): 132-140.
[2]	Shuangxing ZHANG, Fangchen LIU, Yifei ZHANG, Wenjing DU. Experimental study on phase change heat storage and release performance of R-134a pulsating heat pipe [J]. CIESC Journal, 2023, 74(S1): 165-171.
[3]	Yifei ZHANG, Fangchen LIU, Shuangxing ZHANG, Wenjing DU. Performance analysis of printed circuit heat exchanger for supercritical carbon dioxide [J]. CIESC Journal, 2023, 74(S1): 183-190.
[4]	Aiqiang CHEN, Yanqi DAI, Yue LIU, Bin LIU, Hanming WU. Influence of substrate temperature on HFE7100 droplet evaporation process [J]. CIESC Journal, 2023, 74(S1): 191-197.
[5]	Mingxi LIU, Yanpeng WU. Simulation analysis of effect of diameter and length of light pipes on heat transfer [J]. CIESC Journal, 2023, 74(S1): 206-212.
[6]	Zhiguo WANG, Meng XUE, Yushuang DONG, Tianzhen ZHANG, Xiaokai QIN, Qiang HAN. Numerical simulation and analysis of geothermal rock mass heat flow coupling based on fracture roughness characterization method [J]. CIESC Journal, 2023, 74(S1): 223-234.
[7]	He JIANG, Junfei YUAN, Lin WANG, Guyu XING. Experimental study on the effect of flow sharing cavity structure on phase change flow characteristics in microchannels [J]. CIESC Journal, 2023, 74(S1): 235-244.
[8]	Yanpeng WU, Qianlong LIU, Dongmin TIAN, Fengjun CHEN. A review of coupling PCM modules with heat pipes for electronic thermal management [J]. CIESC Journal, 2023, 74(S1): 25-31.
[9]	Jiahao SONG, Wen WANG. Study on coupling operation characteristics of Stirling engine and high temperature heat pipe [J]. CIESC Journal, 2023, 74(S1): 287-294.
[10]	Siyu ZHANG, Yonggao YIN, Pengqi JIA, Wei YE. Study on seasonal thermal energy storage characteristics of double U-shaped buried pipe group [J]. CIESC Journal, 2023, 74(S1): 295-301.
[11]	Cheng CHENG, Zhongdi DUAN, Haoran SUN, Haitao HU, Hongxiang XUE. Lattice Boltzmann simulation of surface microstructure effect on crystallization fouling [J]. CIESC Journal, 2023, 74(S1): 74-86.
[12]	Yitong LI, Hang GUO, Hao CHEN, Fang YE. Study on operating conditions of proton exchange membrane fuel cells with non-uniform catalyst distributions [J]. CIESC Journal, 2023, 74(9): 3831-3840.
[13]	Yubing WANG, Jie LI, Hongbo ZHAN, Guangya ZHU, Dalin ZHANG. Experimental study on flow boiling heat transfer of R134a in mini channel with diamond pin fin array [J]. CIESC Journal, 2023, 74(9): 3797-3806.
[14]	Cong QI, Zi DING, Jie YU, Maoqing TANG, Lin LIANG. Study on solar thermoelectric power generation characteristics based on selective absorption nanofilm [J]. CIESC Journal, 2023, 74(9): 3921-3930.
[15]	Ke LI, Jian WEN, Biping XIN. Study on influence mechanism of vacuum multi-layer insulation coupled with vapor-cooled shield on self-pressurization process of liquid hydrogen storage tank [J]. CIESC Journal, 2023, 74(9): 3786-3796.