Experimental Study Of The Cryogenic Split Heat Pipe Using CO₂ As Working Fluid

Firstly,the history of CO₂ as a refrigerant was reviewed as well as the application fields of CO₂ and theoretic researchs in recent years.The split type heat pipe have advantages of a high heat transfer efficiency, a long distants heat transfer, a easy installation, a small fluid resistance and so on. And the best advantage is that heating and cooling sections can work independently. For all these reasons scholars in many countries have researched on it. But the study on the cryogenic split heat pipe using CO₂ as working fluids have been few reported according to the refrerencs. Under this circumstances,we carried out study about the cryogenic split heat pipe using CO₂ as working fluids,which has the vital significance.Secondly,the design process of the fin-and-tube heat exchangers used in heating section is introduced in detailed and optimization algorithms are used to optimize the structure of the separate type heat pipe. Volume and the heat transfer coefficient of the heat exchanger is taken as an object function respectively, and fin-pitch, tube distance tube rows, row numbers, diameter of heat pipe and the lengths of single pipe are selected as decision variables. Sensibility analysis is also studied base on them. The factors on flow resistance such as cooling capacity, evaporation temperature, diameters of the heating section and cooling section, diameter of the riser-pipe,hight of internal heat exchanger,dryness of refrigerant at outlet of heating section are calculated and analyzed for liquid column height and liquid-filled ratio.Thirdly, the experimental setup of the cryogenic split heat pipe using CO₂ as working fluids was builted based on the optimized results .The performence of cryogenic split heat pipe using CO₂ as working fluid was studied on the setup at different liquid-filled ratio and heat load. According to the experimental results , a relative revamping plan to solve the problem exist durning the experiment each time was put forward and the performance before and after modification was compared.Lastly, the final proposals were put forward based on all the experiments for the reference of further study on cryogenic split type heat pipe.