Abstract The aim of this work is to characterize numerically the performance of a heat pipe flat plate solar collector operating with nanofluids. A mathematical formulation under a 1-dimensional transient heat transfer model was introduced for this purpose. Spatio-temporal temperature variation of each collector subelement was predicted for a typical sunny day in the Moroccan city, Fez. CuO, Al2O3 and TiO2-based nanofluids were compared energetically and exergetically under various operating modes. The nanoparticle loading and mass flow rate of the working fluid were varied in the range of 0–3% and 0.018–0.036 kg/s, respectively. For the flow regime under focus, the decreased specific heat of nanofluids is the main thermal property responsible for the performance enhancement when nanofluids are used. CuO-based nanofluid was found to engender the highest relative enhancements in the energetic and exergetic efficiencies which were estimated at 2.7% and 11.1%, respectively compared to the base fluid (water). Using nanofluids for this collector class can ensure up to 2.95% surplus daily thermal energy generation compared to the base fluid. Moreover, the use of CuO-based nanofluid caused the largest increase in the pressure drop across the collector with a maximum value of 13.26% predicted for 3% nanoparticle loading.

中文翻译：

---

使用纳米流体工作的热管平板太阳能集热器

摘要 这项工作的目的是数值表征使用纳米流体工作的热管平板太阳能集热器的性能。为此，引入了一维瞬态传热模型下的数学公式。预测了摩洛哥城市非斯典型晴天的每个收集器子元件的时空温度变化。CuO、Al2O3 和基于 TiO2 的纳米流体在各种操作模式下进行了能量和能量的比较。工作流体的纳米颗粒负载和质量流量分别在 0-3% 和 0.018-0.036 kg/s 的范围内变化。对于聚焦流态，纳米流体比热的降低是导致使用纳米流体时性能增强的主要热特性。发现基于 CuO 的纳米流体在能量和火用效率方面产生最高的相对增强，与基液（水）相比，分别估计为 2.7% 和 11.1%。与基础流体相比，将纳米流体用于此类收集器可以确保每天产生高达 2.95% 的剩余热能。此外，使用基于 CuO 的纳米流体导致集热器两端压降的最大增加，对于 3% 的纳米颗粒负载预测最大值为 13.26%。