Performance of a reversed circular flow jet impingement bifacial PVT solar collector

Abstract

Photovoltaic thermal technologies, commonly called solar PVT, offer a broad range of advantages in its application. The unique capability of solar PVT allows the production of electrical and thermal energy simultaneously presents a significant advantage. Generally, the PVT solar collector relies on the photovoltaic (PV) module, an integral part of the system. However, the photovoltaic module has a negative downside due to the heat absorbed from being exposed to solar irradiance, which results in a decline in the module’s efficiency. Thus, a cooling system plays a pivotal role in enhancing the efficiency of a PVT collector. There are two common types of photovoltaic modules: mono-facial and bifacial. Compared to mono-facial modules, a bifacial module can potentially absorb energy from the sunlight from both the front and rear surfaces of the bifacial module. However, cooling methods to cool off a bifacial PV module are restricted and lacking as both sides of the PV module are essential and must be exposed to sunlight. Jet impingement is one of the efficient methods that could be used to improve the performance of a bifacial module by improving the heat transfer rate. This study aims to develop, evaluate and analyse the performance of a bifacial PVT solar collector cooled by an air-based reversed circular flow jet impingement (RCFJI). The methodology of this study is categorized into four phases. Phase I includes the Computational Fluid Dynamics (CFD) simulation analysis to determine the best performance design of the RCFJI, leading to the highest bifacial PVT collector performance. The simulation analysis was performed on two distinct cases: the optimum diameter size of the RCFJI and the optimum depth size of the RCFJI. Each design was tested with a mass flow rate of 0.01 0.14kg/s with a solar irradiance of 500-900W/m2. After the design of the RCFJI was determined, Phase II of the study was performed to analyze the energy and exergy analysis by conducting an indoor experiment at the Solar Energy Research Institute (SERI), National University of Malaysia, using a solar simulator. The first case of the indoor experiment was carried out using three bifacial modules with different packing factors of 0.22, 0.33, and 0.66 under a constant solar irradiance of 900W/m2. Meanwhile, the second case was carried out using the highest bifacial module performance, 0.66 under solar irradiance ranging from 500-900W/m2 with a mass flow rate between 0.01 0.14kg/s. The results achieved between the simulation analysis and indoor experiment were compared in Phase III to validate and justify the average percentage accuracy between these two methods. Techno-economic analysis was performed in Phase IV to evaluate the economic performance of the RCFJI bifacial PVT collector. The findings show that the maximum photovoltaic efficiency achieved was 11.38% under 500W/m2 and 0.14kg/s using a 0.66 packing factor, while the maximum thermal efficiency was 61.4% under 900W/m2 and 0.14kg/s. Overall the highest total photovoltaic thermal efficiency achieved was 72.3% at 900W/m2 and 0.14kg/s. Meanwhile, in terms of exergy performance, the highest exergy efficiency achieved was 12.64% at 900W/m2 at 0.06kg/s. The average percentage accuracy between the CFD simulation and the indoor experiment was relatively high, exceeding 90%, indicating a high degree of agreement in the results achieved between the two methods. From the economic point of view, a lower packing factor bifacial module is preferable due to a higher cost-benefit ratio. However, higher packing factors are preferable in terms of energy and exergy performance.