The photoelectric conversion efficiency of photovoltaic thermal (PVT) systems is a key concern in solar energy research. The widespread use of continuous nanofluid cooling in PVT/NPCM (Nano-Enhanced Phase Change Material) systems leads to heightened energy consumption. In order to improve efficiency of the PVT/NPCM systems, a two-dimensional transient heat transfer numerical model is established to analyze the PVT/NPCM system with intermittent flow cooling. Corresponding govern equations with boundary conditions are proposed, and numerically solved by using the finite element method. Simulation results are compared with experimental data, showing a deviation of less than 7 %. The findings indicate that the intermittent cooling reduces the flow energy consumption required to drive 2220 L of nanofluid compared to continuous cooling over a 7-h period. Furthermore, under intermittent cooling conditions, the average electrical efficiency stands at approximately 19.7 %. Notably, the electrical efficiency of PVT/NPCM systems employing intermittent flow cooling closely aligns with those employing continuous flow cooling, exhibiting a maximum deviation of merely 0.0348 %. Additionally, intermittent flow cooling emerges as a favorable choice under solar radiation intensities surpasses 1000W/m, enabling a significant reduction in overall energy consumption while maintaining commendable cooling performance.

中文翻译：

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PVT/NPCM 系统中间歇流冷却和增强光伏效率的综合数值模拟

光伏热（PVT）系统的光电转换效率是太阳能研究的一个关键问题。 PVT/NPCM（纳米增强相变材料）系统中连续纳米流体冷却的广泛使用导致能耗增加。为了提高PVT/NPCM系统的效率，建立了二维瞬态传热数值模型来分析间歇流冷却的PVT/NPCM系统。提出了相应的边界条件控制方程，并利用有限元方法进行了数值求解。仿真结果与实验数据进行对比，偏差小于7%。研究结果表明，与 7 小时内的连续冷却相比，间歇冷却减少了驱动 2220 L 纳米流体所需的流动能量消耗。此外，在间歇冷却条件下，平均电效率约为19.7%。值得注意的是，采用间歇流冷却的 PVT/NPCM 系统的电效率与采用连续流冷却的系统非常接近，最大偏差仅为 0.0348%。此外，在太阳辐射强度超过 1000W/m 的情况下，间歇流冷却成为一种有利的选择，可以显着降低总体能耗，同时保持值得称赞的冷却性能。