Hybrid nanoparticles-laden fluid based spiral solar collector: A proof-of-concept experimental study

Abstract

Over-reliance on limited fossil resources to meet the ever-increasing energy demand has several consequences such as high prices, unpredictable supply, and adverse environmental and ecological impact. It is the need of the current time to explore sustainable renewable energy sources in order to mitigate the environmental consequences and match the increasing demand economically. Out of various sustainable renewable energy sources, solar energy stands out as one of the exemplary candidates. It is a clean energy source with no greenhouse gas (GHG) emissions and is available in abundance at many parts of the world. Prevailing studies corroborate the merit of nanofluids in harnessing solar energy. In this experimental study, thermal analysis of a novel spiral-shaped collector is conducted with both hybrid nanofluid-based volumetric absorption system (VAS) and surface-based absorption system (SAS). In the case of hybrid VAS, homogenous mixture of Al2O3 and Co3O4 with de-ionized water as base fluid is employed. The experimental results reveal that the maximum temperature rise and thermal efficiency of 9.8 °C and 50%, respectively, is obtained at nanoparticle mass fraction of 100 mg/L Al2O3 +100 mg/L Co3O4 which is the optimum mass fraction. Whereas, in the case of SAS, volumetric flow rate of 100 mL/h is the optimum volumetric flow rate at which the maximum temperature rise of 8.5 °C is achieved. Further, the effect of variation in volumetric flow rate and the incident flux on the thermal performance of both VAS and SAS is also presented. On comparing the performance of VAS with SAS under a similar condition a temperature rise and thermal efficiency of about 15.3% and 15%, higher is achieved in VAS than SAS (at optimum volumetric flow rate).