Enhancement of a spiral-tube PV/T collector using nanofluid under hot climatic conditions: experimental study

Abstract

This study experimentally investigates the performance of a spiral-tube photovoltaic/thermal (PV/T) collector integrated with single-crystal silicon PV modules and cooled using Al₂O₃/water nanofluid. Field trials were carried out in Kirkuk (Iraq) in March 2025 under operating conditions. A 0.5 wt% Al₂O₃ nanofluid was used as the working fluid, and its performance was compared to that of flat-plate PV panels under air-cooling conditions and modern water-cooled photovoltaic thermal (PV/T) configurations. 13:00, the nanofluid-cooled collector managed to maintain the PV cell at a minimum temperature of ∼29°C, whereas the water-cooled and air-cooled panels were heated up to about 35°C and 60°C, respectively. Meanwhile, electrical efficiency at this time was 13.4% for the nanofluid-cooled PV/T, 12.6% for the water-block system, and 11.8% for the conventional PV module. The thermal efficiency of the nanofluid PV/T system was approximately 13%, while for water it was 12%. Note also that the net effectiveness was able to reach ~15.1% in the case of the nanofluid system and 14.5% for the water-cooled system. The results indicate that the nanofluid cooling effectively reduces PV cell temperature rise and thereby provides improved electrical, thermal, and overall performance in midday hot situations. In contrast to previous research under moderate weather and on flat plate PV/T systems, the current study experimentally illustrates the feasibility of reliable operation of a nanofluid-cooled spiral-tube PV/T collector in Iraq’s intense heat.