Assessment of Al2O3 nanoparticles for the optimal operation of the flat plate solar collector

The current study deals with the experimental investigation of an Al2O3/water nanofluid-based flat plate solar collector, when the fluid temperature at the inlet of solar collector is influenced by the presence of storage tank (closed loop). The volume fraction of nanoparticles is set to 0.1% with the mean particle size of 20 nm, at three flow rates of 1, 2 and 4 L/min. In this study, the solar radiation and ambient temperature parameters are uncontrollable and presented in a range of transient data of climatic conditions, where these might take place during the spring and summer seasons of Rafsanjan (Iran). The experimental results reveal that adding nanoparticles to a base fluid produces a nanofluid which has enhanced thermal characteristics, as well as the collector efficiency, in comparison to water as an absorbing medium. For any particular working fluid, there is an optimum flow rate, which maximizes the collector efficiency, while in our case study, the nanofluid with the flow rate of 2 L/min is the optimum one and increases the collector efficiency about 23.6%. Meanwhile, the increment of water temperature in the storage tank, confirms that 2 L/min is the optimum flow rate of this specific nanofluid.