Theoretical investigation of the density and the heat capacity of [EMIM][BF4] and its MWCNTs ionanofluids: Effect of temperature and MWCNTs concentration

Abstract

The density and specific heat capacity is an important parameter for heat transfer fluids (HTFs) specially which used for cooling or heating purposes. In this study the density of ethyle methyl imidazolium tetrafluoro borate ionicliquids ([EMIM][BF4]) measured experimentally. In addition, the density (ρ) and the specific heat capacity (Cp) of the ionanofluid (INF) were calculated theoretically. The studied INF composed of multi-walled carbon nanotubes (MWCNTs) dispersed in the ionicliquid (IL) [EMIM][BF4] in the concentrations (0.5%, 1%, 3%, 5%, 7% and 9%). Scanning electron microscopy and differential scanning calorimetry measured for the used MWCNTs. The density and the specific heat capacity of pure [EMIM][BF4] and its INFs were plotted versus temperature in a graphs. The results show that the density of [EMIM][BF4] and its INFs decreased linearly with temperature. The density increased by 0.243%-3.968% for 0.5%-9% MWCNTs concentration in INFs, reaching maximum value of 1.329 g.cm-3 at 20 °C. In contrast the specific heat capacity of [EMIM][BF4] and its INFs increased linearly with temperature with an enhancement of about 0.417%-7.99% for 0.5%-9% concentration of MWCNTs reaching maximum value of 1.812 J/g.K at 358.15K with 9%MWCNT concentration. That’s mean the addition of MWCNT cause increasing both of the density and the specific heat capacity of INF.