Research On The Influencing Factors Of The Heat Storing Performance Of The Thermal Storage Device With High Temperature Concrete

The thermal storage system is a key link in solar thermal technology development and application,and the thermal storage device is the key of the thermal storage system technology work.Solar energy storage with high-temperature concrete,because of its good environmental characteristic and energy saving space,received great attention in both at home and abroad.Internal and overseas,a great deal of research has been carried out on the preparation of high-temperature concrete,but researches for heat transfer research of heat storage unit are still insufficient.In order to resolve this problem mentioned above,it has both theoretical value and important engineering value to carry out the discussion of solar energy storage with high temperature concrete.In this paper,the experiment platform about the concrete storage system was carried out and the temperature filed of the thermal storage unit was tested.Numerical simulation techniques has been used to study the heat transfer process in thermal storage of various factors on the impact of concrete using a three dimensional model to simulate the situation.The obtained results have a comparison with experimental data to verify the correctness of the model.The trend of the experimental data and numerical calculation values are basically consistent,and the relative deviation is less than 9.66%,which verify the correctness of the model.Based on this,numerical simulation on charge performance of thermal storage unit with the concrete as thermal storage medium and the molten salt as the heat transfer medium was carried out.The results show that,the heat storage increases with the increase of coefficient of thermal conductivity of concrete,the rise of inlet temperature,and the increase of fluid flow velocity with other factors unchanged.The spacing of heat exchange tube is 100 mm,the time of concrete heat storage shortest.With the increase of heat exchange tube diameter,the heat exchange area between molten salt and concrete increases,and the concrete heat rate increases,the required amount of steel increases at the same time,which increasing the thermal storage cost.This paper introduces intermittent heat storage model which could improves heat transfer rate,research has shown that intermittent heat storage model can effectively reduce the equivalent charging time of concrete heat storage module.Optimal value of intermittent time was existed in the heat storage unit.The thesis is then based on the simulation model to optimize the structure of heat transfer enhancement,comparing the in the different structure parameters of the ring fin and straight fin.Researches show that the addition of the fin reduce the heat transfer resistance,and improve the coefficient of thermal conductivity.But the ring fin make the concrete section temperature distribution more uniform,more conducive to the long-term use of concrete.