EFFECTS OF ADDITION OF NICKEL FERRITE (NIFE2O4) MAGNETIC DOPANT, SURFACTANT, AND EXTERNAL MAGNETIC FIELD ON THERMAL CONDUCTIVITY OF WATER-BASED NANOFLUID
Heat transfer fluid (HTF) and thermal energy storage (TES) have an important role in improving the efficiency of renewable energy. As a medium of heat transfer, the most important physical parameter of HTF is thermal conductivity. Previous studies have shown that the addition of chemical dopants...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/85300 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Heat transfer fluid (HTF) and thermal energy storage (TES) have an important role
in improving the efficiency of renewable energy. As a medium of heat transfer, the
most important physical parameter of HTF is thermal conductivity. Previous
studies have shown that the addition of chemical dopants of nanoparticles can
increase the thermal conductivity of HTF, known as a nanofluid system.
Furthermore, the use of magnetic dopants and external magnetic fields up to a
certain field value can increase the thermal conductivity of magnetic nanofluid
systems. This experimental study aims to study the effect of the addition of nickel
ferrite (NiFe2O4) magnetic nanoparticle dopants and external magnetic fields on
the conductivity of water-based nanofluids. Dopant characterization includes Xray Diffraction (XRD), Transmission Electron Microscope (TEM), and Vibrating
Sample Magnetometer (VSM) magnetic dopants. The synthesis of magnetic
nanofluids used a two-step method, with dopant concentrations of 0.5; 1; and 2
vol.%. Tetramethylammonium hydroxide (TMAH) surfactant was used for
suspension stability. ,and external magnet using Neodynium permanent magnet
with varied distance to produce magnetic field value of 0-600 G. Thermal
conductivity measurement was done using kd2pro sensor which works based on
transient hot wire (THW) method. The result obtained showed the need of certain
TMAH concentration for nanofluid stability. In general, nanofluid thermal
conductivity decreased with increasing concentration of TMAH surfactant. In
addition, thermal conductivity increased monotonically with increasing dopant
concentration. Furthermore, nanofluid thermal conductivity increased quite
significantly with the addition of external magnetic field. For dopant concentration
of 2 vol.% with dopant:surfactant ratio of 1:0.25 and magnetic field of 600 G,
thermal conductivity value reached 0.842 W/m.K or with ratio of 1.45 compared to
without magnetic field.
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