微槽群结构对微纳复合结构热沉表面汽泡动力学行为影响的可视化研究
发布时间：2018-07-28 11:47
【摘要】：具有微纳复合结构的微槽群热沉是在微槽群热沉的表面镀上一层纳米涂层而形成的。该结构即具有微尺度结构的特性,又具有纳米结构的特性,所以微纳复合结构具有更为特殊的强化换热特性。对具有微纳复合结构的微槽群热沉中的相变换热进行研究,对发展微纳尺度的相变传热理论,具有重要的学术价值;该课题的研究为高热流密度下的电子元器件的散热系统的设计提供了理论依据,对促进我国电子产业的发展,具有重要的实际应用价值。本文采用高速摄影仪对竖直放置的不同微槽群结构的微纳复合结构热沉表面的汽泡动力学行为进行可视化研究。采用划片的工艺在硼硅玻璃板上划刻出不同尺寸的矩形微槽,再采用磁控溅射的方法在微槽表面镀上一层厚度为250nm的钛纳米涂层,形成具有微纳复合结构的微槽群热沉。实验液体工质选用蒸馏水,采用加热和温控系统将蒸馏水温度控制在饱和温度,然后通过陶瓷加热片对微纳复合结构热沉进行加热,使用高速摄影仪观察拍摄微纳复合结构热沉中的汽泡动力学行为,采用数据采集仪对微纳复合结构热沉背部、聚四氟乙烯绝热件的温度进行采集。对实验过程中拍摄的影像使用高速摄影仪自带软件PCC2.3进行逐帧回放和保存,并使用MATLAB的图像边缘化进行进一步处理,计算得到汽泡生长过程中各阶段的当量直径。本文实验过程中将高速摄影仪的拍摄速率设置为6000帧/秒,每两帧的时间间隔为0.17ms,通过查数汽泡周期内的图像帧数,得出汽泡周期和汽泡的等待时间。根据实验研究发现:在相同槽深的微纳复合结构热沉中,相同热流密度下,汽泡当量直径、汽泡周期、汽泡等待时间随微槽深宽比的增大而减小;在微槽群结构相同的微纳复合结构热沉中,汽泡破裂时的当量直径随热流密度的增大而减小;相同热流密度下,与无纳米涂层的微槽群热沉中的汽泡破裂时的当量直径和汽泡周期相比,具有相同微槽群结构的微纳复合结构中汽泡破裂时的当量直径和汽泡周期较小。汽泡周期和汽泡的等待时间均随热流密度的增大而减小,此规律与微槽尺寸变化及热沉表面有无纳米涂层无关。通过上述研究结果表明,与无纳米涂层的微槽群热沉的微尺度结构变化相比,具有微纳复合结构的微槽群热沉的微尺度结构变化对汽泡动力学行为变化的影响更加显著。
[Abstract]:The micro-groove group heat sink with micro-nano composite structure is formed by coating a layer of nano-coating on the surface of micro-groove group heat sink. The structure has the characteristics of both micro-scale structure and nanostructure, so the micro-nano composite structure has more special heat transfer characteristics. The study of phase change heat transfer in heat sink of microgroove group with micro-nano composite structure is of great academic value to the development of phase change heat transfer theory on micro-nano scale. The research provides a theoretical basis for the design of heat dissipation system of electronic components under high heat flux and has important practical application value to promote the development of electronic industry in China. In this paper, a high speed photograph is used to visualize the bubble dynamics of the heat sink surface of different microgrooves with different vertical microgrooves. Rectangular microgrooves with different sizes were carved on the borosilicon glass plate by slicing process, and then the surface of the microgrooves was coated with a layer of titanium nano-coating with thickness of 250nm by magnetron sputtering to form a group of microgrooves with micro-nano composite structure. Distilled water was used as the working medium of the experiment. The temperature of distilled water was controlled at saturation temperature by heating and temperature control system, and then the micro-nano composite structure was heated by ceramic heating sheet. The bubble dynamics of micro / nano composite structure heat sink was observed by high speed photography. The temperature of thermal sink back and PTFE insulation of micro / nano composite structure was collected by data acquisition instrument. The images taken during the experiment are played back and saved by the software PCC2.3 of high-speed photography instrument, and the image marginalization of MATLAB is further processed to calculate the equivalent diameters of each stage in the process of bubble growth. In this paper, the shooting rate of the high speed camera is set to 6000 frames / s, and the interval between each two frames is 0.17ms. by checking the number of image frames in the bubble cycle, the bubble period and the waiting time of the bubble are obtained. According to the experimental results, it is found that under the same heat flux, the bubble equivalent diameter, bubble cycle and bubble waiting time decrease with the increase of the ratio of microgroove depth to width in the same depth micro-nano composite structure heat sink. In the heat sink of micro-nano composite structure with the same microgroove group structure, the equivalent diameter decreases with the increase of heat flux when the bubble ruptures, and at the same heat flux density, Compared with the equivalent diameter and the bubble period of the bubble rupture in the heat sink of the microgroove group without nano-coating, the equivalent diameter and the bubble period of the micro-nano composite structure with the same microgroove group structure are smaller. Both the bubble period and the waiting time of the bubble decrease with the increase of the heat flux, which is independent of the change of the microgroove size and the existence of nano-coating on the surface of the heat sink. The results show that the change of micro-scale structure of micro-groove group with micro-nano composite structure has more significant effect on the dynamic behavior of bubble than that of micro-groove group without nano-coating.
【学位授予单位】：吉首大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB303
本文编号：2150036
[Abstract]:The micro-groove group heat sink with micro-nano composite structure is formed by coating a layer of nano-coating on the surface of micro-groove group heat sink. The structure has the characteristics of both micro-scale structure and nanostructure, so the micro-nano composite structure has more special heat transfer characteristics. The study of phase change heat transfer in heat sink of microgroove group with micro-nano composite structure is of great academic value to the development of phase change heat transfer theory on micro-nano scale. The research provides a theoretical basis for the design of heat dissipation system of electronic components under high heat flux and has important practical application value to promote the development of electronic industry in China. In this paper, a high speed photograph is used to visualize the bubble dynamics of the heat sink surface of different microgrooves with different vertical microgrooves. Rectangular microgrooves with different sizes were carved on the borosilicon glass plate by slicing process, and then the surface of the microgrooves was coated with a layer of titanium nano-coating with thickness of 250nm by magnetron sputtering to form a group of microgrooves with micro-nano composite structure. Distilled water was used as the working medium of the experiment. The temperature of distilled water was controlled at saturation temperature by heating and temperature control system, and then the micro-nano composite structure was heated by ceramic heating sheet. The bubble dynamics of micro / nano composite structure heat sink was observed by high speed photography. The temperature of thermal sink back and PTFE insulation of micro / nano composite structure was collected by data acquisition instrument. The images taken during the experiment are played back and saved by the software PCC2.3 of high-speed photography instrument, and the image marginalization of MATLAB is further processed to calculate the equivalent diameters of each stage in the process of bubble growth. In this paper, the shooting rate of the high speed camera is set to 6000 frames / s, and the interval between each two frames is 0.17ms. by checking the number of image frames in the bubble cycle, the bubble period and the waiting time of the bubble are obtained. According to the experimental results, it is found that under the same heat flux, the bubble equivalent diameter, bubble cycle and bubble waiting time decrease with the increase of the ratio of microgroove depth to width in the same depth micro-nano composite structure heat sink. In the heat sink of micro-nano composite structure with the same microgroove group structure, the equivalent diameter decreases with the increase of heat flux when the bubble ruptures, and at the same heat flux density, Compared with the equivalent diameter and the bubble period of the bubble rupture in the heat sink of the microgroove group without nano-coating, the equivalent diameter and the bubble period of the micro-nano composite structure with the same microgroove group structure are smaller. Both the bubble period and the waiting time of the bubble decrease with the increase of the heat flux, which is independent of the change of the microgroove size and the existence of nano-coating on the surface of the heat sink. The results show that the change of micro-scale structure of micro-groove group with micro-nano composite structure has more significant effect on the dynamic behavior of bubble than that of micro-groove group without nano-coating.
【学位授予单位】：吉首大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB303
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