Thermal Fluid Solid Coupling Numerical Analysis Of Electric Thermal Storage Device Based On Wind Power Dissipation

Wind energy has become the main force in the development of renewable energy because of its wide distribution,no environmental pollution,rich resources and so on.However,there are still many problems to be solved in the development of wind power,such as the integration and absorption of wind power.Especially in the three northern regions,the phenomenon of wind abandonment is more common.At the same time,the valley peak problem of power system is more prominent in our country.When the power grid is in peak load,it pulls the gate to limit the power supply,and when the power grid is in low valley,it stops some units.Frequent start-up and shutdown of units not only increases energy consumption,but also affects unit life.In heating areas,electric heat storage technology is one of the effective ways to solve the problem of wind power grid connection and improve the peak shaving ability of power grid.The system stores heat in the heat storage material by using electric energy during the low valley period or abandoned wind power which cannot be connected to the grid,and provides heat to the users when needed.In this paper,the flow,heat transfer and structural strength phenomena involved in the solid electric heat storage device are simulated and analyzed.A three-dimensional Thermo-Fluid-Solid coupling mathematical model is established to accurately describe the heat conduction,convection,radiation,turbulence and strength under pressure and temperature loads.The temperature,flow,and stress field distribution in the regenerator are obtained by calculation.With the objective of optimizing heat storage and release performance,reducing stress value and stress variation amplitude,the operation parameters of the regenerator are optimized,and the advantages and disadvantages of the different electric heating wires,porosity and single-return structure are compared.The numerical results show that the four surfaces of the regenerator channel are directly radiated by the electric heating wire,and the temperature difference is very small.The maximum average temperature is 885K.After heat storage,the average temperature of the regenerator reaches 763K,which is 281K higher than the initial temperature of 482K.With the increase of heating intensity,the average temperature of the regenerator is basically unchanged,but the temperature difference between inside and outside of the regenerator increases.When the inlet velocity is 28m/s,the temperature of regenerator decreases from 763K to 423K,and the average temperature of outlet fluid is between 389k and 625K.In the heat storage process,under the action of temperature load,the maximum stress increases with time,and the maximum deformation is 0.0286m.By comparing the changes of stress field of regenerator under temperature load,pressure load and their combined action,we can conclude that the maximum stress is 31.5KPa under pressure load,89MPa under temperature load,and 89MPa under two loads.The stress of regenerator is mainly affected by temperature distribution and the influence of pressure can be neglected.The stress of regenerator caused by high temperature and low temperature is the cause of brick failure,and the greater the stress change range,the easier the failure is.Material with smaller linear expansion coefficient can reduce the maximum stress and stress variation amplitude.The regenerator with 72 electric heating wires and 20%porosity has better uniformity in temperature distribution and minimum stress variation.The structure of single and double-return regenerator has its own advantages and disadvantages:the pressure loss of single-return structure is 462.80 Pa and that of doublereturn structure is 1032 Pa.But the heat release rate of the regenerator is faster.The existence of expansion joints can reduce the stress and stress variation amplitude,and avoid faults caused by excessive thermal stress or stress variation.In summary,the heat-fluid-solid coupling multi-field coupling mathematical model of solid electric heat storage device is established in this study.The temperature distribution,flow field,and stress distribution in the heat storage device are shown in detail.The results of optimization of operation parameters and structure can provide basis for the practical application of the heat storage device.