碟式聚光斯特林系统地面混凝土桩储热研究

Heat Storage Research of Ground Concrete Piles in Disc Focusing Stirling System

为了解决碟式太阳能斯特林发电系统的储能问题,建立1 kWβ型碟式斯特林发动机储能的地上混凝土储热单元,采用计算流体力学方法,针对熔融盐流速v、储热时间t、换热管管径D、熔融盐初始温度T对混凝土桩蓄热量Q和对流换热系数h的影响进行双因素分析。结果表明:v与Q呈线性关系,但v的增大导致接触时间减少而不能充分换热,最佳流速为3 m/s;D越大达到相同Q所需时间就越短,但大管径会导致混凝土体积降低、蓄热量减少,管径为25 mm最佳;随着v的增加达到相同h所需温度越低;h随D的增大而减小,D越大达到相同h所需温度越高。通过优化管型,采用S型换热管,使得对流换热系数、蓄热量、蓄热效率都较直型换热管有所提高。

In order to solve the energy storage problem of dish solar Stirling power generation system,the ground concrete heat storage unit of 1 kWβ⁃type dish Stirling engine was established,and the computa⁃tional fluid dynamics method was adopted to carry out the two⁃factor analysis of the influence of molten salt flow rate v,heat storage time t,heat exchange tube diameter D and initial molten salt temperature T on concrete pile heat storage Q and convective heat transfer coefficient h.The results show that there is a linear relationship between v and Q,but with the increase of v,the contact time decreases and the heat transfer can not be fully done,the optimum flow velocity is 3 m/s;The larger D is,the shorter the time required to reach the same Q is,but the larger tube diameter will lead to the decrease of concrete volume and heat storage,and the best tube diameter is 25 mm;with the increase of v,the temperature required to reach the same h is lower;h decreases with the increase of D,and the larger D is,the higher the tem⁃perature required to reach the same h is.By optimizing the tube type and adopting S⁃shaped heat ex⁃changer tube,the convective heat transfer coefficient,heat storage and heat storage efficiency are higher than that of straight heat exchanger tube.