Effect Of Ionic Liquid On Absorption Properties Of Nanofluids And Intermolecular Interaction Study

The problem of depletion of fossil fuels has become more serious,forcing people to find more renewable energy sources to solve the current energy shortage problem.As we all know,solar energy is the most potential renewable energy source.Solar collectors can convert sunlight into heat or electricity to satisfy people's everyday needs,where the collector fluid plays a key role in the efficiency of the collector.To the best of our knowledge there are few studies about the effect of the anion or cation radius on the absorption properties of nanofluids.Therefore,in this paper,we focus on the research of high-efficiency collector fluid selection method.The effects of anions and cations on the absorption properties of nanofluids are systematically studied by selecting several ionic liquids with wide liquid range,high thermal decomposition temperature and different anions and cations.In this paper,nine Fe₃O₄/ionic liquid-based nanofluids with the same mass fraction are prepared by two-step method.These ionic liquids contain different anion and cation radii.These pure ionic liquids and corresponding nanofluids were then measured for transmission in the 200-2100 nm band using an ultraviolet-visible near-infrared spectroscopy.The results show that the transmittance spectra of the nine pure ionic liquids have relatively small differences,which proves that the transmittance of pure ionic liquids are relatively high.However,the corresponding transmittance spectra of nanofluids are quite different.When the anions of the ionic liquids are the same,as the cation radii increase,the transmittance of the corresponding nanofluids gradually decrease,that is,the absorption performance gradually increase.This is because as the radii of the cation increase,the viscosity gradually increase,and the diffusivity gradually decrease,resulting in a more uniform dispersion of the entire system and better absorption.When the cations are kept constant,as the anion radii increase,the transmittance of the other four nanofluids decrease except for the nanofluid containing the[EMIM][Ac]ionic liquid.It is speculated that when the anion radii are increased,a larger space can be provided to cause a more uniform dispersion of the two-phase system,so that a better absorption effect is obtained.We provide new ways of understanding these phenomenons by analyzing the sample from the perspective of intermolecular interactions.The terahertz spectrum of nine pure ionic liquids and corresponding nanofluids were detected by the terahertz time-domain spectroscopy system?detected band range was 0.4-3.5 THz?.The results show that when the anions are constant,as the cation radii change,the added nanoparticles could have effect on intermolecular forces between the anions and cations.When the cations are constant,as the anion radii change,however,the intermolecular forces between the anions and cations is unable to explain the effect of added nanoparticles.