a b s t r a c t In this study, the effects of the volumetric flow rate of the nanofluid (250 ml/min, 350 ml/min, 450 ml/ min and 550 ml/min) and the mass fraction of the nanoparticles (0 wt%, 0.2 wt% and 0.5 wt%) on the energy and exergy efficiencies of an indirect solar cooker with multi-walled carbon nanotube-oil (MWCNT-oil) nanofluid are investigated. Moreover, the performance of the solar collector and cooking unit, as the two main parts of the indirect solar cooker, is analyzed from the energy and exergy viewpoints. The results reveal that while increasing the volumetric flow rate of the nanofluid enhances the energy and exergy efficiencies of the solar collector, those of the cooking unit are maximized at the flow rate of 250 ml/min. Furthermore, using the nanofluid with a higher nanoparticles mass fraction leads the energy and exergy efficiencies of the solar collector and cooking unit to increase. Based on the results, the overall energy efficiency of the nanofluid-based solar cooker with 0.5 wt% is 20.08%, and the relative improvement of the overall exergy efficiency of the nanofluid-based solar cookers with 0.2 wt% and 0.5 wt% compared to that of the cooker with thermal oil is 37.30% and 65.87% respectively. © 2020 Elsevier Ltd. This is an open access

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