【作者】 张凯；

【导师】 辛公明；

【作者基本信息】 山东大学 ， 动力工程及工程热物理， 2021， 硕士

【摘要】 槽道热管利用热管内壁的槽道结构提供毛细力,促使工质能够顺利回流从而完成循环过程,进而实现热量的输送,其结构简单、可靠性高,气液两相携带作用较小,槽道与热管之间的热阻小,二次加工性能好,因此得到了广泛的关注和研究。本文采用实验方法,首先分析讨论了槽道的结构参数对热管传热性能的影响,并对比了不同工质对典型槽道热管运行特性的影响,最后实验研究了基于太阳能应用的长水平热管的传热特性。主要研究内容如下:(1)自主设计制造了一批具有不同槽道规格的槽道热管,搭建了热管性能测试平台,完成了具体实验方案的设计,给出了实验数据的处理方法,最后对实验系统的不确定度进行了分析。(2)实验研究了选取水作为工质的槽道热管传热性能,并与内壁无槽道结构的重力热管进行了对比,分析了内壁加工槽道以及结构参数对热管性能的影响。分析实验数据发现:槽道结构的存在对热管水平角度运行性能提升明显;壁厚较小的热管性能更好;壁厚和槽道深度相互制约,小功率下壁厚影响较大,大功率下槽道深度影响系数变大;槽道深度和数目相互依存,小功率下数目影响系数大,大功率下槽道深度影响系数大;槽道深度较大时,槽道数目的影响系数变大。(3)实验研究了不同工质在槽道热管水平角度下的传热性能,并与水工质热管进行对比分析,分析发现0.15wt%正庚醇溶液能够强化热管性能;0.10wt%正庚醇溶液热管的传热性能较差,在较小的加热功率下发生了“烧干”现象,说明浓度变化对自湿润流体热管传热性能影响较大;无水乙醇热管传热性能与水接近,但是传热极限得到较大提升,这与其较小的接触角有关;两种乙二醇溶液的热管传热极限较小,不适合热管大功率工况运行。(4)针对太阳能热管工作特性,选取了前文中低功率下热管传热性能较好的三种工质,研究了其在长水平太阳能热管的运行特性。通过对比研究发现自湿润流体的太阳能热管启动时间最短,蒸发段温度、热阻远远小于其他两种工质;无水乙醇与乙二醇热管的传热性能接近,但无水乙醇在较大功率工况下表现更佳。更多还原

【Abstract】 The grooved heat pipe is a heat pipe that uses the grooved structure to provide capillary force to make the liquid working medium return so as to realize heat transmission.Its structure is simple,the reliability is high,the gas-liquid two-phase carrying effect and thermal resistance between the grooved and the heat pipe are small.It has very good secondary processing performance,and will not fall off the wick and tube wall during the flattening and bending process,so it has received extensive attention and research.In this paper,the effects of structural parameters of grooved heat pipe on heat transfer performance of heat pipe are studied and expressed through test approach,and the feedback of different working fluids on the operation features of grooved heat pipe are contrasted.Finally,the running situation of large length horizontal solar heat pipe is talked over.The main research contents are as follows:(1)A batch of grooved heat pipes and solar heat pipes with different grooved structures are designed and manufactured independently,a performance test platform is built,the design of the experimental scheme is completed,the experimental data processing method is determined,and the uncertainty of the experimental system is calculated.(2)The heat transfer performance of grooved heat pipe is collected by running test with using water as working medium,compared with conventional gravity heat pipe,and the impact of shape data on heat conductivity is discussed.It is found that the existence of grooved structure can strengthen the heat transfer of heat pipe;The wall thickness and grooved depth restrict each other.The influence of wall thickness is greater at low power,and the influence coefficient of grooved depth becomes larger at high power;The grooved depth and number are interdependent.The number influence coefficient is large at low power,and the grooved depth influence coefficient is large at high power.When the grooved depth surpasses a certain numerical value,the influence factor amount of the grooved becomes larger.(3)The heat transfer performance of different working medium grooved heat pipes at different horizontal angles is experimentally studied and compared with that of hydraulic medium heat pipes.It is found that 0.15wt%n-heptanol solution can strengthen the heat transfer of heat pipes;The heat transfer performance of 0.10wt%nheptanol solution is poor,and the phenomenon of drying occurs under small heating power;The results show that the solution consistence effects the heat transfer performance of self-wetting fluid heat pipe;The heat transfer coefficient of absolute ethanol heat pipe is similar to that of water,and the limit power increases more,which is related to its small contact angle;The heat transfer limit of the two glycol solution heat pipes is small,which is not suitable for high-power working conditions.(4)According to the working characteristics of solar heat pipe,three working fluids with good heat transfer performance under low and medium power are selected to study their operating characteristics in long-level solar heat pipe.It is found that the self-wetting liquid solar heat pipe has shortest start-up time,and the temperature and thermal resistance of evaporation section are much lower than the other two working fluids;Absolute ethanol and ethylene glycol heat pipes have similar heat transfer performance at low power,but absolute ethanol has better heat transfer performance at high power.更多还原