Analysis And Structure Study On Heat Storage And Release Process Of Solid Heat Accumulator

Solid heat accumulator is a device that converts electric energy into heat energy by the off-peak electricity at night and stores it in the heat accumulator,and then converts and outputs the heat when the heat is needed.It plays an important role in the realization of energy saving and emission reduction and the peaking and valley filling of the power grid.At present,there is relatively little theoretical research on solid heat accumulator at home and abroad.In practical engineering applications,solid heat accumulator has the possibility of further improvement in the aspects of heat storage capacity,temperature field and flow field distribution uniformity.The traditional structure of the heat accumulator is stacked with a fixed heat accumulator brick.The brick structure is single,and the heat accumulator channel is also formed by the heat accumulator brick stack.Therefore,the uniformity of the temperature distribution of the heat accumulator is difficult to be guaranteed.In view of the above constraints,this topic from the perspective of structural optimization,put forward a new heat storage structure,by comparing the traditional heat storage and heat release performance of the structure,to prove the feasibility of its practical application.The main work of this thesis includes:(1)In order to improve the heat storage and release capacity of solid heat accumulator in practical engineering applications and improve the uneven distribution of temperature field and flow field in the heat storage and release process of solid heat accumulator,the heat transfer analysis model is used to determine the internal temperature distribution and heat transfer rate expression of the heat accumulator,and analyze the factors affecting the heat transfer process.A kind of hexagonal magnesium brick structure is proposed based on the analysis results and the design specification of special shaped brick.Based on the improved brick type,a new heat accumulator structure is proposed,which can effectively solve the problem of unequal heat conduction rate of the brick layer around the heat storage hole,and improve the uniformity of the overall temperature distribution of the heat accumulator.(2)For engineering commonly used solid heat accumulator,combined with the heat transfer theory of heat storage and discharge process,the thermodynamic properties of magnesium brick and the structural characteristics of the heat accumulator,the simulation analysis of heat storage process adopts the thermal analysis method with non-constant physical parameters,and the simulation analysis of heat discharge process adopts the coupling analysis method of heat flow and solid with non-constant physical parameters.The heat storage and release process of solid heat accumulator was numerically simulated,and then the feasibility of experimental tests is confirmed by using an efficient laboratory model and the errors are analyzed separately.(3)By using the numerical simulation method of heat storage and heat release process which has been verified by experiment,the heat storage and heat release process of the new heat storage structure is analyzed,and the calculation results are compared with the heat storage and heat release process of the traditional heat storage structure,which can verify the feasibility of the practical application of the new heat storage structure proposed in this thesis.In the process of heat storage,the temperature difference of each monitoring point of the new accumulator at the same heat storage time is reduced by 119.2 K compared with that of the traditional accumulator.Under the same target heat storage temperature,the heat capacity of the accumulator is increased by 16%,and the heat storage performance is effectively improved.In the process of heat release,the temperature distribution and flow field distribution of the new heat accumulator are more uniform,which reduces the occurrence of eddy current effect,and the rate of average heat fall is above that of the traditional thermal storage structure,and the thermal discharge performance is enhanced effectively.