Capabilities of advanced heat transfer fluids on the performance of flat plate solar collector
Gabriela Huminic, Angel Huminic
Abstract
The main goal of the current paper is to investigate the effect of advanced heat transfer fluids including ionanofluids and nanofluids with several base fluids (ionic liquid, water and ethylene glycol) on the thermal performace of a flat-plate solar collector (FPSC). The FPSC under real weather conditions was analyzed. In the current research, the advanced heat transfer fluids investigated are: [Bmim]BF4 (1-butyl-3-methyl imidazolium tetrafluoroborate), [Bmim]BF4 + graphene, [Bmim]BF4 + single-wall carbon nanotube with concentrations of 0.005 and 0.01 wt%, [C4mim]NTf2 (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), [C4mim]NTf2 + aluminum oxide, water, water+aluminum oxide, ethylene glycol, and ethylene glycol+aluminum oxide with concentrations of 0.18, 0.36 and 0.90 vol%. FPSC efficiency is compared to existing correlations for figure-of-merits (FOMs). Results indicate that the thermal efficiency depends on the base fluid and the type of nanoparticle and varies with the nanoparticles concentration. The use of [C4mim]NTf2 + 0.9 vol% Al2O3 in FPSC led to relative enhancement in thermal efficiency by about 54.08%, 26.05% and 17.54% compared to water + 0.9 vol% Al2O3 at Re= 100, 200 and 300. The results also show that not all analyzed FOMs correlations are in agreement with the collector efficiency. Furthermore, the comparative study carried out emphasized that ionic liquids are a good alternative to conventional fluids (water) to be used in solar collectors under Romanian weather conditions.