Optimum concentration of carbon black aqueous nanofluid as coolant of photovoltaic modules: A case study

Nowadays, photovoltaic technology has been recognized as a popular energy source in most parts of the world. The temperature rise in photovoltaic cells is one of the major weak points of this technology which impacts on its electricity generation. Using nanofluid circulation as the coolant of photovoltaic modules, is one of the methods concerned by scholars. In this paper, using carbon black nano particles in water was investigated experimentally, and the concentration range of 0–0.4 wt% were tested. Results showed an unexpected cooling behavior of carbon black/water nanofluid. So that, the concentration of 0.21 wt% was found to be the best case. This concentration led to produce 7% more output power in comparison with pure water as coolant and 54% more output power in compare with the conventional photovoltaic module. In order to precisely calculate the electrical energy efficiency, the consumed pumping power was considered, too. The exergy assessment is another investigated matter in this paper and a modified method for exergy efficiency calculation is presented. Accordingly, the overall exergy efficiency rises 15.2% and the entropy generation depresses 1.4% compared with the conventional module, for the best case.