Passive solar module cooling based on hydrogels beads and nanofluids


From pv magazine Global. 

Researchers from Egypt’s Benha University and the University of Bristol in the United Kingdom have a developed a new passive technology to cool off solar modules, based on saturating hydrogels beads that use nanofluids instead of water. 

Hydrogels beads are micro-sized particles with cooling properties that are made from natural or synthetics polymers and are commonly applied in biomedical, drug delivery, and biological studies. Aluminium oxide (Al2O3) water-based nanofluids with three different concentrations were used by the scientists as a saturation agent for the hydrogels beads.

Dry hydrogel beads were mixed with the nanofluids through a sonication process, which applies sound energy to agitate particles or discontinuous fibers in a liquid. “Three nano particles weights were measured in fume cabinet and mixed with water to get three percentage’ weight concentrations of (0.1%, 0.25% and 0.5%),” the academics explained.

The experimental set up.Image: University of Bristol

The saturated beads were then placed below the back surface of simulated PV panels and the cooling solution was tested at standard test conditions radiation with a temperature between 30 and 3 degrees Celsius, relative humidity between 40 and 50% around the panels’ surface, and a wind speed close to near zero. “The panel temperature was measured using 3 K-type thermocouples attached to each back surface and connected to data loggers,” the British-Egyptian group specified.

The experiment showed that the simulated panels with the hydrogels beads exhibited better thermal performance compared with both the uncooled panel and the hydrogel solution that was saturated only with water. “The optimised concentration of 0.5%wt. Alumina-water based nanofluid could significantly reduce the temperature by 17.9 and 16.3 degrees Celsius compared with the uncooled panel at radiation intensities of 800 and 1000 W/m2, respectively,” the academics affirmed. “The optimised concentration could enhance the electricity efficiency of the panels by approximately 10.1%.”

The additional analysis of the costs of the proposed technology showed, the researchers went on to say, that payback time ranges from 16.1 and 12 years at radiation intensities of 800 and 1000 W/m2, respectively. “It can be noticed that due to the expensive cost of the nano material, by increasing the concentration of the nanofluid, the payback period increases,” the research team explained.

“The technology is already viable for commercial production,” research co-author, Saber Abdo, told pv magazine.

The passive cooling technique is presented in the study Effect of using saturated hydrogel beads with alumina water-based nanofluid for cooling solar panels: Experimental study with economic analysis, published in Solar Energy.

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