Theoretical model for flat plate solar collectors operating with nanofluids: Case study for Porto Alegre, Brazil

Abstract

The present work aims to investigate the theoretical model of a flat-plate solar collector considering nanofluids as heat transport medium. For this purpose, solar irradiance decomposition and transposition models have been implemented. Also, the different models for determining the thermophysical properties of nanofluids were implemented and compared with experimental data on these properties. The theoretical model was implemented in Matlab software and validated by comparison with experimental data from a flat-plate solar collector with MgO water. The results show that the maximum relative error was 5.36%, the minimum relative error was 0.20%, and the mean relative error was 2.02% when the model was validated with experimental data for MgO-water nanofluid with volume concentrations between 0 and 1.5%. Therefore, the theoretical model was successfully extended to simulate flat-plate solar collectors with MgO-water nanofluid. A parametric study showed that a nanofluid with a volume concentration of 0.75% MgO exhibited a higher relative increase in thermal efficiency compared to pure water. Moreover, the theoretical model was applied to a case study by simulating the annual performance of the collector in Porto Alegre, Brazil, when it was operated with MgO water. This showed satisfactory effects and great potential for application.