太阳能斯特林混凝土储热系统传热特性研究

HEAT TRANSFER PERFORMANCE OF CONCRETE THERMAL STORAGE SYSTEM FOR SOLAR ENERGY STRILING

设计碟式太阳能斯特林机混凝土储热系统,并对熔融盐及混凝土传热过程进行理论分析,对混凝土储释热过程进行模拟,运用多目标遗传算法进行优化,得到以下结论:在释热过程,选取290℃为流体出口的有效温度临界值,有效释热时间约2.1 h时,流体出口温度约为563 K,释热效率约为71%;高温混凝土和熔融盐沿着流程方向均存在一个温跃层区域,随着时间的延长,温跃层沿着流程方向逐渐向下游偏移,当温跃层移动到出口处时,熔融盐出口温度开始下降,温跃层占据的长度越小,储热系统效率越高;随着导热系数的增加,释热效率及有效释热时间提高。通过TOPSIS对解集进行重新排序分析,最优工况是蓄热量为2885 MJ、换热系数为672 W/(m·K)及储热效率为87%。

The concrete heat storage system of the solar dish type Stirling machine is designed,the molten salt and concrete heat transfer process are theoretically analyzed,the concrete heat storage and release process is simulated,and the multi-objective genetic algorithm is used for optimization.The following conclusions are obtained.In the heat release process,290℃is selected as the critical value of the effective temperature of the fluid outlet.When the effective heat release time is about 2.1 h,the outlet temperature of the fluid is about 563 K,and the heat release efficiency is about 71%.High temperature concrete and molten salt have a thermocline area along the direction of the process.With the extension of time,the thermocline also gradually moves downstream along the direction of the process.When the thermocline moves to the outlet,the outlet temperature of molten salt begins decreasing and the shorter the length of the thermocline is,the higher the efficiency of the heat storage system is.With the increase of thermal conductivity,the heat release efficiency and effective heat release time increase.The solution set was reordered by TOPSIS,and the optimal conditions were heat storage of 2885 MJ,heat transfer coefficient of 672 W/(m·K)and heat storage rate of 87%.