Researches On The Performance Of R134-a Pulsating Heat Pipe Phase Change Accumulator

In the critical period of our carbon peaking and carbon neutrality goals,the domestic energy structure is rapidly transforming from fossil energy to renewable energy.Heat storage technology has been widely concerned by scholars because it can effectively solve the incongruity of solar energy,wind energy and other renewable energy in time and space.Phase change materials are widely used in latent heat storage because of their high latent heat and high stability.However,low thermal conductivity is not conducive to energy storage and release.The excellent heat transfer performance of pulsating heat pipe can effectively make up for this disadvantage of phase change materials.In this paper,pulsating heat pipe is taken as the research object,studies the heat transfer performance and heat storage/release performance of pulsating heat pipe under different working conditions through experiments,and the enhanced heat transfer technology of heat accumulator is studied by numerical simulation,these work can provide reference for the design and optimization of pulsating heat pipe accumulator.The primary studies include:(1)According to the operation principle and working environment of pulsating heat pipe,the pulsating heat pipe is designed independently,and the working medium of pulsating heat pipe is selected.The performance test platform of pulsating heat pipe was built,experimental input parameters and performance indexes of pulsating heat pipe were set up,and experimental errors and uncertainties were analyzed to ensure the accuracy and reliability of subsequent experimental results.(2)The influence of different working medium and the number of elbows on the heat transfer performance of pulsating heat pipe was studied experimentally.According to the experimental results,the five-elbow pulsating heat pipe was selected,and R134-a and acetone were used as the working medium for heat storage pulsating heat pipe.The influence of heating power,liquid filling rate,dip Angle and other factors on the performance of pulsating heat pipe for heat storage was further studied,the results show that the optimum dip Angle and filling rate of different working medium are different,and the R134-a pulsating heat pipe has the best heat transfer performance and the highest stability.The experimental results select pulsating heat pipe with excellent heat transfer performance for subsequent heat storage and release experiments.(3)The phase change accumulator of pulsating heat pipe was designed,and the experimental system of pulsating heat pipe-PCM coupled heat storage and release was built.The feasibility experiments of three operating modes of heat storage only,heat release only and synchronous heat storage and release were carried out,and the characteristics of heat storage and release under different modes were obtained.The influence of heating power,cooling water temperature,cooling water flow and other factors on the heat storage and release performance of the heat accumulator was further studied,and the main performance parameters of the heat storage time,heat release and heat storage and release efficiency under different working conditions were obtained.(4)The process of PCM heat storage and heat release in the heat storage unit was simulated numerically.By orthogonal analysis of the length,distance and thickness of the heat transfer fin,the fin structure with the best heat storage performance within the design parameters is obtained.The influence of different fin parameters on the heat storage process of the heat accumulator is analyzed,and the difference of fin action in the heat storage and heat release process is compared,the results showed that the fin structure promoted the heat storage process better than the heat release process.