Abstract The purpose of this two-part study is to present the experimental analysis carried out on a naturally ventilated Building Integrated Photovoltaic (BIPV) system and the new correlations developed for the estimation of the convective heat transfer coefficients (CHTC) in the air gap, and use the developed correlations to construct a simulation model which is validated with the experimental data. In BIPV systems the air gap is responsible to cool the PVs and remove excess heat to avoid building overheating. The ventilation of the air gap can be natural or mechanical. However, naturally ventilated systems are less studied although they have important advantages over the mechanically ventilated ones, such as the avoidance of extra energy of the fans, maintenance and noise. The present Part I of this study presents an experimental based thermal analysis of a naturally ventilated vertical BIPV system. A series of experiments on a custom made BIPV system were carried in real outdoor conditions as well as indoors with the use of a large scale solar simulator to measure the thermal characteristics of the system and its thermal behaviour. Indoor experiments were performed to avoid external disturbances from wind that may occur outside. The results show that an open-ended air gap of 0.1 m can create adequate air flow on naturally ventilated systems and can ensure low PV temperatures to avoid PV efficiency decrease. The experimental data are then used to estimate the convective heat transfer coefficients to fit the real conditions of the BIPV systems. Then two correlations are proposed for the estimation of the Nusselt number that fits best the thermal characteristics of a naturally ventilated BIPV system.

中文翻译：

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第一部分：自然通风 BIPV 系统的热分析：实验研究和对流传热系数估计

摘要 本研究分为两部分，目的是介绍对自然通风建筑集成光伏 (BIPV) 系统进行的实验分析，以及为估算空气间隙中的对流换热系数 (CHTC) 而开发的新相关性，并使用开发的相关性来构建仿真模型，该模型通过实验数据进行验证。在 BIPV 系统中，气隙负责冷却 PV 并去除多余的热量以避免建筑物过热。气隙的通风可以是自然的或机械的。然而，尽管自然通风系统比机械通风系统具有重要的优势，例如避免风扇的额外能量、维护和噪音，但研究较少。本研究的当前第一部分介绍了自然通风垂直 BIPV 系统的基于实验的热分析。一系列针对定制 BIPV 系统的实验在真实的室外和室内条件下进行，使用大型太阳模拟器来测量系统的热特性及其热行为。进行室内实验是为了避免可能发生在室外的风的外部干扰。结果表明，0.1 m 的开放式气隙可以在自然通风系统上产生足够的气流，并可以确保较低的光伏温度以避免光伏效率下降。然后使用实验数据来估计对流传热系数，以适应 BIPV 系统的实际条件。