Researchers in the Middle East have developed a new design for energy systems in which the production of solar electricity is combined with the Trombe walls of buildings. They claim that their new system configuration with reflective mirrors improves overall system efficiency for both heating and power generation.
Its developers describe a photovoltaic/Trombe wall (PV/TW) system as a system that can produce hot water, hot air and electricity, and the TW system is also used to cool the temperature of the PV module. TWs are also often designed with reflective mirrors to enhance energy production, and porous materials, phase change materials (PCM) or nanofluids can be used to improve overall system efficiency.
With their work, the researchers strive to find the best angle of inclination of the reflective mirrors with the ultimate goal of improving both the thermal and electrical power of the system. “The effect of reflective mirrors was investigated by introducing a DC fan and a heat exchanger, studying the effect of different weather conditions on both systems to ensure the performance of the photovoltaic Trombe wall,” they explained.
The experimental setup consists of two chambers with solar panels and reflective mirrors. One of the chambers uses a heat exchanger placed behind the PV modules, while the other does not have a heat exchanger. The mirrors were placed on the right and left sides of the south face of the system and fixed to the ground with an iron base. Each chamber is 1.25 m long, 2 m high and 1.25 m wide.
The researchers tested three different angles of inclination of the mirrors, 30, 45 and 60 degrees. The performance of the system was tested using temperature sensors and an Arduino system. Two DC fans and two bottoms were installed on top of each chamber, and a water pump was used to circulate water inside the heat exchanger.
“In this study, the electrical and thermal performance of the (PV/TW) system was evaluated by determining the heat absorption rate of the duct air and the heat absorption rate of the heat exchanger and calculating the electrical power that the solar panel can produce.” they explained. “The temperature, current and voltage values ​​of each PV panel, as well as the inlet and outlet temperatures of the water, fans and indoor space are recorded every hour.”
Through their analysis, the researchers found that the best angle of inclination for a reflective mirror on a heat exchanger is 30 degrees. They said this system configuration allows for the highest daily electrical efficiency of 13.86%. “The use of water passing through a heat exchanger behind the PV panel increases overall performance by lowering the temperature of the PV panel,” they added, noting that the PV panel temperature is also lowered by the PV/TW system’s DC fan.
The system is described in a study published in 2010 “Optimum angle of reflective mirrors integrated into PV/Trombe wall: Experimental evaluation”. Energy reports. The group includes researchers from Al-Kitab University and Northern Technical University in Iraq. “For future recommendations, it is suggested to investigate the effect of phase change materials (PCM) in the PV/Trombe system with the use of mirrors and a dual air duct,” they concluded, pointing to a direction for future research.
