Scientists in China have demonstrated a photovoltaic-thermal system that uses Tesla valves to increase cooling and efficiency. The system was found to have better performance compared to PVT systems made with different cross-sectional structures.
Researchers from Donghua University in China have designed a photovoltaic-thermal (PVT) system that uses a Tesla valve to improve cooling performance.
A Tesla valve is a passive, one-way valve line with a fixed geometry. It was designed and patented by Nicola Tesla about 100 years ago and is intended to move fluid in one direction without moving parts. “Tesla valves can improve heat transfer by creating swirls and turbulence in the fluid flow, increasing the heat transfer coefficient and reducing the temperature difference between the fluid and the solid surface,” the scientists said.
Through a numerical simulation, the research group developed a PVT module consisting of a glass cover, a PV panel, a heat-absorbing plate, a flow channel, liquid, ethyl vinyl acetate (EVA) encapsulant and Tesla valves.
The academics then assessed the cooling performance of the panel with the Tesla valves, assuming the use of four different fluids, namely water, magnesium oxide (MgO), titanium oxide (TiO2) and aluminum oxide (Al2O3). They emphasized that the cooling effect is significantly affected by the speed increase.
“In particular, when the velocity is within the range of the turbulent critical value up to 1 m/s, the increase in flow velocity has a significant effect on reducing the PV temperature,” they pointed out. “However, when the flow velocity was greater than 1 m/s, there was no significant cooling effect with the increase in flow velocity.”
The simulation showed that the PVT system with the Tesla valves achieved an electrical efficiency of 16.32% and a thermal efficiency of 59.65%. These results were then compared with those of identical PVT systems based on three different cross-sectional structures and the analysis showed that the flow channel of the Tesla valve structure provides superior thermal and electrical efficiency.
The scientists also identified optimal parameters for the Tesla valves, such as an angle of 30 degrees and a tube diameter ratio of 1.
Their findings can be found in the article “Numerical study of photovoltaic/solar thermal systems with Tesla valve,” published in scientific reports. Looking ahead, they said they want to test nanofluids in the proposed system configurations. “Nanofluids have the potential to achieve rapid cooling and heat storage,” they concluded.
Image: Donghua University, Scientific Reports, Creative Commons License CC BY 4.0
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