Experimental investigation of the effect of multi-wall carbon nanotube – Water/glycol based nanofluids on a PVT system integrated with PCM-covered collector

Abstract A hybrid PVT/PCM system is constructed to experimentally examine the effect of water/glycol-based nanofluids as active cooling media and organic paraffin wax (PCM) as passive cooling medium. Multi-wall carbon nanotubes (MWCNT) are considered as the nanoparticles, due to their high thermal conductivity that allows using a lower concentration of these nanoparticles and reduces the flow pressure drop and pumping power consumption. The electrical and thermal performances of the PVT/PCM system are evaluated regarding energy and exergy views compared to the experimental results of a conventional PV module (without a thermal collector). The exergy destructions and external exergy losses are also evaluated based on their contributing factors. The best performance of PVT/PCM panel in terms of relative enhancement of the electrical energetic and exergetic efficiencies is obtained for the MWCNT/water nanofluid. Dispersion of MWCNT nanoparticles in the water base fluid increases the thermal and electrical energetic efficiencies up to 23.58% and 4.21%, respectively as compared to those of pure water as coolant fluid. A corresponding enhancement is also observed for the electrical and particularly the thermal exergetic efficiencies. The major influencing factors for external exergy losses and exergy destructions of the system are found to be heat dissipation from the PVT panel to surrounding and sun-PVT surface temperature difference, respectively.