Numerical Study On The Operation Process Of Closed Loop Pulsating Heat Pipe

In recent years,with the continuous development of electronic equipment,the requirements of high power,small size and high performance are also increasing.In this context,pulsating heat pipe as a high-efficiency heat exchanger is more and more widely used in the field of electronic equipment heat dissipation.Compared with traditional heat sinks,pulsating heat pipes have the advantages of simple structure,low thermal resistance and high reliability,which can effectively improve heat dissipation efficiency and reduce system temperature,providing a guarantee for the reliability and performance of electronic devices.However,there are some shortcomings in the previous research of pulsating heat pipe.In this paper,the heat transfer mechanism of pulsating heat pipe is studied in detail in terms of flow characteristics,temperature distribution,pressure distribution and thermal resistance for the pulsating heat pipe used in electronic equipment,and the numerical study of the operation process of pulsating heat pipe is carried out.analysis,and the importance of the factors affecting the heat transfer performance was determined by orthogonal experimental design.The main work is as follows:(1)A two-dimensional numerical model of the pulsating heat pipe was established using relevant theoretical models,and the growth of the gas-liquid plug,the flow characteristics of the working mass and the heat transfer characteristics of each part of the pulsating heat pipe at each stage during the process from start-up to stable operation were analyzed.(2)The influence of individual variables on the heat transfer performance of the pulsating heat pipe was analyzed using the control variable method,and it was found that the pulsating heat pipe showed the best performance when water was used as the working medium,followed by acetone,methanol and ethanol.With the increase of heat source power,the thermal resistance showed a trend of decreasing and then increasing,and the heat source power exceeded a certain value,the pulsating heat pipe could not transfer the excess heat generated by the heat source,and the thermal resistance would increase sharply.The study of the work fluid filling rate found that the best performance of the pulsating heat pipe work fluid filling rate at 50%.(3)Designed orthogonal experiments to analyze the influence of multiple factors on the heat transfer performance of the pulsating heat pipe,and found that the order of importance of different factors on the operation of the pulsating heat pipe is: work material type,heat source power,work material filling rate.And the best combination was obtained.Through orthogonal test analysis,a more in-depth understanding of the performance parameters affecting the pulsating heat pipe was obtained.(4)The empirical correlation formula of heat transfer coefficient of heat conduction for small electronic devices was obtained with a coefficient of determination of 0.9054.The empirical correlation equation has a good fitting accuracy within the scope of this paper and has the potential to be a valuable tool for future design,optimization,and analysis of pulsating heat pipes.