Economic and performance analysis of modified solar distillation system coupling different integrations using Carbon Quantum Dot (CQD) nanoparticles: Generalized thermal model

Clean drinking water and electricity production utilizing non-conventional sources of en-ergy is the global demand for the sustainability development. Ultrafast heat transfer fluids have delivered impressive results in photovoltaic integrated solar thermal systems, in recent times. Ef-forts have been made for the productivity and electricity augmentation of solar still equipped with helically coilled heat exchanger and coupled with different integrations viz. (a) partially covered N- photovoltaic thermal compound parabolic concentrator (N-PVT-CPC), (b) partially covered N- photovoltaic thermal flat plate collector (N-PVT-FPC), (c) N- FPC-CPC (d) N- flat plate collector (N-FPC). System design has also been modified adding roof-top semi-transparent PV module and built-in-passive copper condenser (circulation mode); and effect of carbon quan-tum dots (CQDs)- water based nanofluids, nanoparticles volume concentration and packing fac-tor (βc) of the PV module have been studied by developing generalized thermal modelling of the system (special cases). Overall, 41.1%, 21.52%, 22.01%, and 10.01% rise in evaporative HTCs is observed in FPC-CPC, PVT-CPC, FPC, PVT-FPC integrations respectively. Thermal exergy is found to be higher for FPC-CPC integration and it follows the enhancement order as FPC-CPC (max-0.147 kW) > PVT-CPC (0.088 kW) > FPC (0.038 kW) >PVT-FPC (0.028 kW). In refer-ence to the base-fluid, significant enhancement in the daily productivity is observed for FPC-CPC (10.9%) and PVT-CPC (5.16%) integrations using CQD-NPs. Production cost of potable water have also been estimated for all the cases for n=30 and n=50 years life span and i=4% and 8% interest rates; and it found to be lowest (0.014 $/lt) for FPC-CPC integration using CQD NPs (n=30 year, i=4%).