Compared with two tank thermal energy storage (TES) system, the single-tank thermocline (STTC) TES system provides a more cost-effective option for TES systems with low-cost solid filler, and it is progressively becoming an important research topic. In this study, analytical approach solutions derived from the one-dimensional two-phase (1D-2P) without heat loss model and one-dimensional one-phase (1D-1P) with heat loss model in the STTC system are compared with experimental data, it is found that local thermal equilibrium assumption is inappropriate in the thermocline tank because the internal heat transfer in fluid and solid is dominant. Besides, the analytical approach results of 1D-2P model are more exact than numerical results compared with experimental data. The algebraic equations of non-dimensional discharging time and discharging efficiency are derived from analytical modeling results. Based on these important correlations, a multi-parametric optimization design procedure of the thermocline tank considering of stress safety requirement is proposed. Then different design cases are studied and the effects of some critical non-dimensional parameters are investigated. The results show that optimal Pe number exists for designing a thermocline TES system, with which convection heat transfer is dominant and final discharging time is not that short. For the PROMES experimental case, not only the output power increases 145.9% but also the final discharging efficiency improves 0.75% compared with the experimental boundary condition with the optimum Pe = 960.63. Larger value of fluid volumtric heat capacity ratio and higher Bi number increases efficient discharging time and discharging efficiency while decreases thermocline thickness, the improvement is highly significant especially for Bi < 1 × 10⁶.

与两罐式热能存储（TES）系统相比，单罐式热跃线（STTC）TES系统为带有低成本固体填料的TES系统提供了更具成本效益的选择，并且正逐渐成为重要的研究课题。本研究将STTC系统中无热损失模型的一维两相（1D-2P）和有热损失模型的一维一相（1D-1P）解析方法与实验数据进行了比较，发现在热跃罐中局部热平衡的假设是不合适的，因为流体和固体中的内部传热是主要的。此外，与实验数据相比，一维二阶模型的解析方法结果要比数值结果更为精确。从解析模型结果推导了无量纲放电时间和放电效率的代数方程。基于这些重要的相关性，提出了考虑应力安全要求的温跃层储罐的多参数优化设计程序。然后研究了不同的设计案例，并研究了一些关键的无量纲参数的影响。结果表明最优存在用于设计温跃线TES系统的Pe号，对流传热占主导地位，最终排放时间不短。对于PROMES实验情况，与最佳Pe  = 960.63的实验边界条件相比，不仅输出功率增加了145.9％，而且最终放电效率提高了0.75％。更大的流体体积热容比值和更高的Bi值增加了有效的放电时间和放电效率，同时减小了热跃层的厚度，尤其对于Bi  <1×10 ^6而言，这种改进意义重大。