Evaluation of the thermal efficiency of ethylene glycol/magnetite nanofluids for use in direct absorption solar collectors

This research evaluates the efficiency of working fluids in direct adsorption solar collectors by incorporating magnetite (Fe₃O⁴) nanoparticles. Samples with Fe₃O₄ concentrations ranging from 0% to 1% were evaluated under direct solar exposure conditions. It was determined that the nanofluids exhibit higher thermal efficiency than pure ethylene glycol, indicating that magnetite enhances solar radiation absorption. However, higher nanoparticle concentration was observed to decrease the Specific Absorption Rate (SAR), likely due to lower radiation penetration. These results suggest that SAR could be a useful selection criterion for formulating nanofluids in DASC collector applications.