numerical investigation of the effect of hybrid nanofluid on the efficiency of direct absorption solar collector

In the current work, the effect of using hybrid nanofluid on the thermal performance of direct absorption parabolic trough solar collector were examined numerically by implementing a multiphase approach. the use of this volumetric absorber was delivered because of some of its characteristics, such as optimum optical properties, which can lead to higher efficiency. in order to study the effects of different nanofluids, mwcnt-al2o3/water hybrid nanofluid in three volume concentrations, its single nanofluids, and pure water were compared to each other. the methods of mixture approach and eulerian-eulerian approach were implemented in this study. in addition, the effects of different solar intensities on both outlet temperature and efficiency of the solar collector were examined. obtained results verify that by using hybrid nanofluid in a volume concentration of 0.02%, the efficiency of the direct absorption solar collector increases up to 14.9% and 25.1% compared to al2o3/water nanofluid and pure water, respectively.