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Nanoparticle based direct absorption oscillating heat pipes for solar thermal systems

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Nanotech improvement to solar energy

The solar energy sector needs improvements in efficiency and innovation in the generation of electricity to stay relevant. Researchers have developed improvements to solar energy generation systems using cutting-edge nanotechnology and heat pipes.

Energy
Fundamental Research

Developing sustainable solar energy technology is increasingly important to secure our energy future. With fast-diminishing fossil fuels and increasing concerns around global warming, sustainable and renewable energy technologies like solar need to step up to meet energy demands. The EU-funded NANODAOHP (Nanoparticle based direct absorption oscillating heat pipes for solar thermal systems) initiative worked to improve on the limitations of solar thermal technology using nanotechnology and phase-change approaches. The researchers systematically addressed efficiency challenges associated with the prototype, from suitable direct-absorption nanofluid formulation to performance in oscillating heat pipes. With this innovative technology, researchers used direct-absorption nanoparticles to overcome the surface-controlled heat transfer limitation to absorb solar energy directly in the carrying fluid. NANODAOHP chose gold (Au), silver and copper (Cu) direct-absorption nanoparticles for this application. They chose these materials because of their strong local surface plasmonic resonance effect. The researchers also used oscillating vapour bubbles (in oscillating heat pipes) to drive the fluids instead of pumps. The team carried out a study to address the challenges associated with this new concept from direct nanofluid formulation to its performance in the oscillating heat pipe. Researchers observed that the absorption efficiency can be largely increased by using hybrid nanofluids such as Au-Cu. They found that Au-Cu hybrid nanofluid enhanced solar photothermal conversion across the visible light range. Under focused solar radiation, NANODAOHP observed a strong steam evaporation phenomenon, which is beneficial to the start-up and steady running of an oscillating heat pipe. NANODAOHP fabricated metal and transparent oscillating heat pipes and found the performance of the new system to be highly dependent on nanoparticle type, morphology and concentrations. Through these results, several potentially long-term collaborations between China and Europe have been established. These will allow significant knowledge transfer into Europe, especially in the field of heat pipe systems.

Keywords

Solar energy, NANODAOHP, direct absorption, oscillating heat pipes, nanofluid formulation

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