基于火积理论的多级套管式相变蓄热系统优化

本文基于最小火积耗散热阻原理，在考虑相变材料导热热阻以及非稳态传热过程的基础上，对多级套管式相变蓄热系统的融化温度进行了数值优化，获得了最优融化温度分布。在此基础上，研究了相变材料导热系数和传热管长度对最优融化温度、火积耗散热阻和平均蓄热速率的影响。研究结果表明，与现有理论优化方法相比，本文提出的数值优化方法具有更好的适用性；优化后多级套管式相变蓄热系统可有效提高相变蓄热系统的平均蓄热速率，降低火积耗散热阻；随着相变材料导热系数增大和传热管长度增加，多级套管式相变蓄热系统最优融化温度的温差愈加明显，其强化传热性能呈上升趋势。

Optimization of multistage shell-and-tube LHTES system based on entransy theory

The melting temperatures of multistage shell-and-tube latent heat thermal energy storage (LHTES) system were numerically optimized based on the minimum entransy dissipation-based thermal resistance principle, which considered the thermal resistance of phase change material (PCM) and transient heat transfer process. The optimal melting temperature distribution of the multistage shell-and-tube LHTES system was obtained. Furthermore, the effects of PCM thermal conductivity and tube length on optimal melting temperature, entransy dissipation-based thermal resistance and average heat storage rate were investigated in this work. The results showed that the numerical optimization method has a wider applicability in comparison with the theoretical optimization method. The average heat storage rate is increased and the entransy dissipation-based thermal resistance is decreased effectively for the optimized multistage shell-and-tube LHTES system. As the PCM thermal conductivity and tube length increase, the optimal melting temperature difference of multistage shell-and-tube LHTES system increases, and the enhancement performance is improved more obviously.