Potential of simple and hybrid nanofluid enhancement in performances of a flat plate solar water heater under a typical North-African climate (Tunisia).

This work aims to quantify the long-term performance improvement of solar water heater system by using both simple and hybrid nanofluids. For this purpose, transient system simulations of a flat plate solar collector have been carried out and discussed using titanium oxide, magnesium oxide, and copper oxide/multiwalled oxide-carbon nanotube nanofluid-based nanoparticles. Tunisian climatic conditions with a typical household need has been considered, and the investigations have been established in terms of energy amounts, solar fractions, and harmful CO emission avoidance. Results showed an increase in the collector performances using the considered nanofluids. In particular, using 0.2v% and 0.6v% TiO homogeneously dispersed in water reduced the auxiliary energy up to 47.6 and 60.9%, respectively, compared to the reference case using water. The flat plate solar collector has an annual production of 1294 kWh for a need of 1998 kWh, which equates to an annual coverage rate of roughly 65%. Additionally, it was shown that when MgO with MWCNT were used instead of MgO nanofluid-based nanoparticles, the solar fraction increased by 5.14%. The use of 0.6 volume percent TiO nanoparticles in water reduces hazardous CO emissions by up to 0.829 tons annually.