EFFECTS OF ADDITION OF NICKEL FERRITE (NIFE2O4) MAGNETIC DOPANT, SURFACTANT, AND EXTERNAL MAGNETIC FIELD ON THERMAL CONDUCTIVITY OF WATER-BASED NANOFLUID

• Main Author: Adnan Mahmudi, Riyadi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85300
• Institution: Institut Teknologi Bandung

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.