Stability and thermophysical properties of fly ash nanofluid for heat transfer applications

Abstract

Improving the performance of heat transfer fluids is altogether significant. The best approach for improving the thermal conductivity is the addition of nanoparticles to the base fluid. In the present study, specific heat, dynamic viscosity, and thermal conductivity of water-based Indian coal fly ash stable nanofluid for 0.1% to 0.5% volume concentration in the temperature range of 30 to 60°C has been investigated. To evaluate an average particle diameter of 11.5 nm, the fly ash nanoparticles were characterized with scanning electron microscopy and dynamic light scattering. Using zeta potential, the stability of nanofluid in the presence of surfactant Triton X-100 was tested. Thermal conductivity and viscosity of fly ash nanofluid increased, while specific heat decreased as volume concentration increased. The effect of temperature on the fly ash nanofluid was directly proportional to its thermal conductivity and specific heat and inversely proportional to viscosity.

Influence of particle size on thermal conductivity and dynamic viscosity of water‐based Indian coal fly ash nanofluid

“…37 If the absolute value of ζ lies between ±30 and 40 mV was stable, ±40 and 60 mV had good stability, above 60 mV has excellent stability, and less than ±30 mV was agglomerative. 38,39 In the present study, the ζ was measured using a Zeta sizer (Malvern Instruments) at 25°C for 0.5 vol% concentration of different particle sizes at a pH of 7.5-8.…”

Heat transfer characteristics and entropy generation analysis in a plate heat exchanger using ethylene glycol and water mixture‐based Al2O3 nanofluid

“…From the study, it was observed that 10.29% enhancement in viscosity was found for 2% of weight concentration at 20°C compared with base fluid. Brownian motion and van der Waals forces are the primary contributors 53,54 for the increase in viscosity of nanofluid. Accordingly, for 0.2, 0.5, 1, and 1.5 wt% concentration, the CHTC obtained was 6.43%, 14.25%, 23.61%, and 28.94% greater than that of base fluid respectively.…”

Nanofluids effect on the overall transfer coefficients change mechanism analysis

“…The thermal conductivity of nanofluids increased with temperature and concentration. Other nanofluids thermal conductivity coefficiencies, for instance, the ash nanofluids thermal conductivity and viscosity would increase, but the specific heat would decrease when the volume concentration increased 29 30 and the results indicated the TPF thermal performance factor values increased with the concentration increasing.…”

“…Other nanofluids thermal conductivity coefficiencies, for instance, the ash nanofluids thermal conductivity and viscosity would increase, but the specific heat would decrease when the volume concentration increased. 29 The researcher studied the heat transfer, entropy generation and pressure drop of fly ash-Cu hybrid nanofluid under turbulent flow in a tube, 30 and the results indicated the TPF thermal performance factor values increased with the concentration increasing.…”