Enhancing photovoltaic-thermal module performance with Tesla valves

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Researchers at the Donghua University in China have designed a photovoltaic-thermal (PVT) system that utilizes a Tesla valve to increase cooling performance.

A Tesla valve is a passive, one-directional valvular conduit with a fixed geometry. It was designed and patented by Nicola Tesla around 100 years ago and is intended to move fluid in a single direction without any moving parts. “Tesla valves can enhance heat transfer by creating vortices and turbulence in the fluid flow, which increases the heat transfer coefficient and reduces 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, fluid, ethyl vinyl acetate (EVA) encapsulant, and Tesla valves.

The academics assessed then 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 stressed that the cooling effect is significantly affected by the speed increase.

“In particular, when the velocity lies within the range of the turbulent critical value to 1 m/s, the increase in flow velocity has a significant effect on lowering the PV temperature,” they stressed. “However, when the flow velocity exceeded 1 m/s, there was no significant cooling effect with the increase in flow rate.”

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The simulation showed that the PVT system with the Tesla valves was able to achieve 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 Tesla valve structure flow channel offers superior thermal and electrical efficiency.

The scientists also identified optimal parameters for the Tesla valves such as an angle of 30 degrees and a pipe diameter ratio of 1.

Their findings can be found in the paper “Numerical study on solar photovoltaic/thermal system with Tesla valve,” published in scientific reports. Looking forward, 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.

Temperature cloud map with different runner structures: (a) rectangle; (b) triangle; (c) semi-circle; (d) Tesla valve.

Image: Donghua University, scientific reports, Creative Commons License CC BY 4.0

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