An experimental investigation on the performance of a flat-plate solar collector using eco-friendly treated graphene nanoplatelets–water nanofluids

The research on the use of nanofluids in thermal energy devices, like solar collectors, has secured a high place in the scientific community of recent years. In the present study, the effects of clove-treated graphene nanoplatelet nanofluids on the performance of flat-plate solar collector were investigated. For this, the graphene nanoplatelets and clove buds were covalently functionalized using the one-pot technique. Zeta potential test was conducted to check the stability of the graphene nanoplatelets–water nanofluid and found highly stable for 45 days. In the next step, three different mass concentrations 0.025 mass%, 0.075 mass% and 0.1 mass% were synthesized. The thermal performance of flat-plate solar collector at these three concentrations of the nanofluids of three different mass flow rates 0.0133, 0.0200 and 0.0260 kg s −1 m −2 was investigated in the next step. The results revealed that the thermal performance of solar collector enhances with the increase in mass concentration and mass flow rates and decreases with an increase in reduced temperature parameter. The highest thermal performance of a solar collector has reached 78% at mass concentration 0.1 mass% and flow rate 0.0260 kg s −1 m −2 which is 18.2% higher than water at the same flow rate conditions.