Cooling technology for PV modules based on individual channels with nanofluids – pv magazine International
Scientists in Mexico have developed a new cooling technology for solar panels that is expected to increase the power generation of photovoltaic modules by up to two percent. The system uses nanofluids embedded in an aluminum channel attached to the back of the module.
Researchers from the Mexican University of Sonora (UNISON) and the National Institute of Technology of Mexico have conducted a numerical study of the thermal performance of a single-channel cooling system for photovoltaic modules.
In their simulation, they used different types of nanofluids, such as aluminum oxide (Al₂O₃), copper(II) oxide (CuO) and zinc oxide (ZnO). In addition, they equipped the system with baffles, which are structures placed in a cooling channel to improve heat dissipation.
“The system includes nine evenly distributed baffles that act as deflectors. The baffles are inclined at 45 degrees and 1 cm high. They favor the contact of the cooling fluids with the back of the panel, thus increasing the effective heat transfer coefficient,” the group explained.
The model included the five layers that make up a 13% efficient photovoltaic module – glass, ethylene vinyl acetate (EVA), solar cell, Tedlar and thermal paste – as well as the proposed 3 cm high aluminum channel through which the cooling liquid circulates. “This cooling liquid can be either a nanofluid or pure water,” the scientists explained.
The numerical model was built using Ansys Fluent v20 software based on the finite volume method. The PV system model and the flow of nanofluids in the laminar flow regime were validated against previous literature results and showed a “reliable basis for modeling PV systems and their interaction with nanofluids”.
In all cases, the metal oxides were suspended in water, with varying volume concentrations of 0, 0.01, 0.05, and 0.1, respectively. They used a range of Reynolds numbers (Re), which are used as a measure to determine whether the fluid flow is uniform or chaotic, between 18 and 42. A fluid inlet temperature of 34 °C was assumed.
The scientists found that the CuO nanofluid was the most effective, improving efficiency by 5.67% over pure water in the lowest Re range. “The 0.1 vol. concentration in the nanofluid causes a more effective temperature reduction of the photovoltaic cell, reaching up to 15% when the Reynolds number increases from 18 to 42. Increasing Re from 18 to 42 increased the electrical efficiency by 4%,” they further explained.
In addition, the group found that increasing the nanofluid concentration from 0 to 0.1 improved the electrical efficiency by 1.40%, and that increasing the radiation from 200 W/m2 to 1,000 W/m2 reduced the efficiency by 6.5% for pure water and 5.5% for the nanofluid. “Baffles improve heat transfer in specific channel regions, resulting in a 2% increase in electrical efficiency by redirecting and accelerating fluid flow,” they concluded.
The cooling system was presented in the “Numerical study on the thermal performance of a single-channel PV cooling system using baffles and various nanofluids” published in Heliyon.
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