Research On Design Method Of Phase Change Energy Storage Tank Based On Dual Objective Optimization Of Phase Change Heat Transfer Enhancement And Flow Drag Reduction

The phase change energy storage technology is an energy storage that uses phase change materials with physical state changes to absorb or release a large amount of latent heat.Phase change energy storage technology can effectively improve the availability and stability of renewable energy.By shifting the peak to fill the valley,it can also improve the usage efficiency of power equipment and reduce electricity costs.Due to its higher energy density,good controllability of charging and releasing processes,and easy availability of raw materials,the phase change energy storage technology is widely used in thermal management technologies such as environmental control,building envelope and electronic equipment cooling.Phase change materials,as the core of phase change energy storage systems,play a crucial role in the heat transfer performance and rapid response to peak loads of the system.However,the thermal conductivity of phase-change materials is generally lower,which seriously affects the heat transfer process of phase change materials and the charging/discharging rate of the system.It can also bring the problem of slow transient response of the energy storage system.The above mentioned is the biggest obstacle faced by the current phase change energy storage technology.Adding fins to a phase change energy storage system is a simple and efficient methods of enhancing heat transfer.The heat transfer performance of the overall system can be enhanced by expanding the heat transfer area between the phase change material and the heat transfer fluid.However,most of the experimental and simulation studies on finned tubes are more complex,and the time period for obtaining results is long,resulting in less research on the dual objective optimization of heat transfer rate and flow resistance in phase change energy storage systems with finned tubes.Therefore,based on ε-NTU method,thermal resistance analysis method,and thermal resistance heat capacity heat transfer network model,this study establishes a dynamic analytical model that can quickly solve the phase change process.The accuracy of the model has been verified through the experimental results of a phase change cold storage device embedded in a heat pipe and the experimental results of a spherical stacked phase change energy storage tank,which preliminarily proves the effectiveness and universality of the simulation model.Based on this,this study establishes an experimental platform of a phase change energy storage tank system with finned tubes.The water is adopted as the heat transfer fluid,and No.35 paraffin is used as the phase change material to conduct experimental research on its energy charging and release processes.The temperature changes of the phase change material(paraffin)and the temperature of the heat transfer fluid inlet and outlet sides are obtained.Then,a dynamic analytical model is established for the experimental platform,and a comparison is made between the actual temperature at the outlet of the heat transfer fluid and the simulated value to verify the accuracy of the model.It can be used for the study of multi-objective optimization design of the experimental device.A large number of operating conditions and finned tube size parameters are set.Based on the model calculations,the heat transfer rate and flow resistance under corresponding conditions are calculate.Through multiple linear regression method,the optimization objective function of the two and 100 Pareto optimal solutions are obtained.Finally,an entropy weighted double basis point method is used to find a compromise optimal solution from these optimal solutions.The corresponding operating conditions and finned tube size parameters are the results of the dual objective optimization design.This study can provide a certain theoretical basis for the optimization design of phase change energy storage devices with finned tubes in the future.