Performance analysis of hybrid nanofluids in flat plate solar collector as an advanced working fluid

Nanofluids are innovative fluids. Hybrid fluids are engineered by mixing of different nanoparticles in suitable proportion with conventional fluid, in order to achieve desired thermo physical parameters. In present work, authors have investigated response of flat plate solar collector when conventional working fluid, water is replaced by nanofluids. The selected nanofluids are hybrid of CuO and MgO with MWCNTs with water base. Experimentation performed under varying concentration from 0.25% to 2.0% and varying flow rate (0.5 lpm to 2.0 lpm) for both nanofluids under given ambient condition. Quantitative and qualitative responses of flat plate collector have been observed by energetic and exergetic performance evaluation of the collector. Increase of Bejan number is an indication of system's quality credit. It enhances productive entropy due to transfer of heat caused by temperature difference and suppresses production of entropy, arises by systems irreversibilities. Findings strongly supports optimum operating conditions for flat plate solar collector are concentration of particles in range of 0.75-1.0% at mass flow rate 0.025-0.03 kg/s. Exergetic and energetic efficiency of collector for hybrid nanofluid are 71.54% and 70.55% for MgO hybrid nanofluid. Under similar parameters exergetic and energetic efficiency of collector for CuO hybrid is 70.63 and 69.11%. Percentage enhancement in exergetic and energetic efficiency of collector for MgO hybrid nanofluids are: 25.1% with respect to base fluid and 16.28% with respect to MgO/water fluid. As hybrid nanofluid MgO performs better than CuO hybrid and closer to MWCNTs/water fluid.