Analysis Of Influence Of Water Tank Structure And Inlet Pipe Arrangement On Thermal Characteristics Of Solar Thermal Storage Tank

In a solar water heating system,the thermal characteristics of the storage tank has played essential roles in the overall performance of the system.The thermal characteristics of the solar thermal storage tank are not the same in the charging process and the discharging process.However,the structure of water tank and the arrangement of water inlet pipe have direct influence on the heat storage and heat release performance of water tank.The author studied the charging process and the discharging process of the storage tank through literature research,theoretical analysis and numerical simulation.In the process of water storage of tanks,the effects of different water tank structure types on the charging characteristics of the tanks were analyzed.During the discharging process of tanks,the effects of different water inlet pipe layout methods on the heat release characteristics of the water tanks were analyzed.The heat storage tank structure with better thermal characteristics and the arrangement of inlet pipes is proposed.In the charging process of the water tank,under the condition that the capacity of the water tank and the heating coil are the same,three kinds of heat storage tanks of different structures are studied,namely a cylindrical water tank,a circular table-shaped water tank and a spherical water tank,and different heat storage workers are set up.In addition,the effect of the tank structure on the temperature stratification and heat storage efficiency of the water tank was investigated.The analysis shows that in thethree tank structures,the circular table heat storage tank is conducive to improving the heat storage characteristics of the tank.In addition,four circular table-shaped water tanks with different top-down radius ratios(n)were proposed,and the heat storage performance under different heat storage conditions was analyzed.In the circular table heat storage tank,as the ratio of the upper and lower radius of the tank decreases,the temperature stratification effect increases,and the heat storage efficiency of the water tank first increases and then decreases;when the ratio of the upper and lower tank radii is n=0.554,the water tank Temperature stratification and heat storage efficiency are excellent.To evaluate the heat storage performance of the tank,the temperature stratification effect of the tank and the heat storage efficiency of the tank should be taken into consideration.In the discharging process of the water tank,two inlet pipes are tangentially arranged outside the water tank.The authors studied the influence of the arrangement of inlet pipes on the discharging characteristics of tanks when there are different consumption of hot water per unit time under the conditions of heat input and no heat input.The results show that the two branches of the water inlet pipe are tangentially arranged on the outside the lower part of the tank,which improves the discharging characteristics of the water tank to some extent.Under the condition of heat input,when the water consumption per unit time of the water tank is small,the negative tangential angle is beneficial to the release of heat from the water tank;when the water consumption per unit time of the water tank is large,the positive tangential angle is favorable to the tank discharging.Under the condition of no heat input,when the water consumption per unit time of the water tank is small,the negative tangential angle is more favorable to the tank discharging;when the water consumption per unit time of the water tank is larger,the tangential angle ??15° is better for the tank discharging.