یک مطالعه تجربی و نظری در مورد افزایش عملکرد سیستم دیوار ترومب/فتوولتائیک
Abstract
1- Introduction
2- Methodology
3- Experimental work
4- Mathematical model formulation
5- Results and discussions
6- Conclusions and recommendations
References
Abstract
The hybrid Photovoltaic/Thermal systems are suffering from the low electrical performance as a result of elevated its temperature. Present work attempts to enhance the performance of a hybrid Photovoltaic/Trombe wall (PV/TW) system through employing a porous medium. In this article, the effect of porous medium, DC fan and glass cover on the performance of a PV/TW was accomplished by the design and implementation of an experimental system to achieve this target. The mathematical method to predict the performance of a PV/TW system was also offered based on a simplified concept of an energy balance. The results of the theoretical study agreed well with the practical results in terms of the estimated temperature of the solar cell. The results revealed that incorporating the porous medium and DC fan offered favorable features of the system performance, while the glass cover has a conflict effect. It was confirmed that using porous medium and DC fan reduces the temperature of PV cell and increases the room temperature. Whereas, the presence of the glass cover in front of the system leads to elevate the temperatures of the room and solar cell. The presence of porous medium with DC fan increases the values of thermal and electrical efficiencies about 13% and 4%, respectively. Furthermore, the combined effect of porous medium with DC fan and glass cover increases the values of thermal and electrical efficiencies about 20% and 0.5%, respectively. It is recommended to integrate the PV/TW system with DC fan and porous medium for further conversion of solar radiation and improve building comfort conditions.
Introduction
The world today is facing the energy crisis, as it has become one of the most important problems due to the large and continuous increase in energy consumption that depletes conventional energy sources. In addition, there is a limited reserve of conventional energy resources, as well as a significant rise in fuel prices and environmental problems [1]. Research and studies have begun focusing on renewable energy, especially solar energy, to address conventional energy problems and replace it with a clean and environmentally friendly option [2]. The Trombe wall is one of the passive solar systems that take advantage of the available solar energy in nature and converts it into heat without any electrical or mechanical assistance. A Trombe wall is always fixed on the southern façade of buildings in the northern hemisphere to increase solar energy throughout the year. The principles of the Trombe wall are described as shown in Fig. 1. It consists of a wall of concrete for heat storage and the wall is dyed with a black color to increase absorption of solar radiation. There are layers of glass at 5e10 cm distance from the concrete wall to increase the intensity of solar radiation [3]. In the past decades, modern technologies that use solar cells to generate electricity have been introduced. A photovoltaic (PV) cell can be integrated with buildings in diverse ways (rooftops, façades, PV/Trombe wall (PV/TW),…etc.). The PV cell in such hybrid system not only produces the electricity but also helps in heating, day lighting, and reduces cooling/heating loads, as well adds the aesthetic of the building [4]. Generally, these hybrid systems can be classified into PV/Trombe wall, building-integrated photovoltaic (BIPV) system, and PV/thermal collector. These hybrid systems are more efficient than separate solar thermal and electrical systems [5,6].