Study On Random Heat Transfer Of Phase Change Heat Storage Device

In a large number of heat transfer processes,the influence factors of heat transfer process are often random.Therefore,if the randomness of influencing factors can be taken into account in the design process,the reliability and safety of equipment operation can be improved,and the system cost can be reduced.Phase change heat storage has great potential in thermal energy storage.In this paper,the uncertain heat transfer phenomena of phase change heat storage devices are studied.It is hoped that the relevant research can provide reference for the study of uncertain heat transfer.Firstly,the uncertain heat transfer model of vertical phase change heat storage device is established.Based on the model,the heat storage and release processes of vertical phase change heat storage device are analyzed.By combining the interval number analysis method in uncertain mathematics with the finite difference method,the model regards the range of uncertain factors as an interval number,and uses the perturbation method to solve the model.The simulation results show that considering the uncertainty in the heat transfer process of the phase change heat storage device is very necessary for the rational analysis of the whole heat transfer process of the phase change heat storage device.Secondly,the random heat transfer of phase change heat storage device was experimentally studied.According to the theoretical basis of previous analysis,the latent heat of phase change of different phase change heat storage materials during exothermic process is equivalent to internal heat source,and the random change of latent heat of phase change heat storage materials is simulated by constructing random change of internal heat source.The experimental study on the uncertainty of latent heat value of phase change heat storage materials is carried out.The influence of different probability distribution of internal heat source,uncertainty of internal heat source(standard deviation)and wind speed of different medium on standard deviation of outlet temperature is analyzed.The experimental results show that the standard deviation of the air outlet temperature increases with the increase of the standard deviation of the input internal heat source.The standard deviation of air outlet temperature increases with the increase of the average power of the input internal heat source.The standard deviation of air outlet temperature at low wind speed is higher than that at high wind speed under the same input internal heat source.When the probability distribution of internal heat source is normal or uniform,the standard deviation of air outlet temperature is close,which shows that the probability distribution of different internal heat sources has no obvious effect on unstable heat transfer.Because the theory of linear system under stochastic excitation is very mature,the current research on stochastic heat conduction mainly focuses on the application of stochastic models to solve the problem of linear heat conduction.In this paper,the phase change heat transfer,a non-linear heat transfer phenomenon,is studied theoretically and experimentally.The theoretical research carried out in this paper can give a more realistic mathematical description of the heat transfer process of phase change heat storage device.In addition,a new idea for the study of uncertain heat transfer is also presented in this paper.Relevant research methods can provide reference for the study of uncertain heat transfer process.