TY  - MANSCPT
AU  - Hizanorhuda Binti Zurghiba
TI  - Enhanced heat transfer in low-concentration cellulose nanocrystal-copper automotive nanocoolants
SN  - THE0010172 (Local)
PY  - 2025///
CY  - Kuantan, Pahang
PB  - UMPSA
KW  - Faculty of Mechanical and Automotive Engineering Technology
KW  - Dissertations
KW  - Universities and colleges
N1  - Faculty of Mechanical and Automotive Engineering Technology; Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2025; Includes bibliographical references
N2  - Extensive study has been conducted in the field of nanocoolant due to the increasing industrial demand. Stability of nanocoolants at higher volume concentrations is a significant challenge as the particles increase the fluid's viscosity and accelerate the oxidation and corrosion of radiator components. Thermophysical properties of CuO or CNC single nanocoolants in EG are well established; however, limited studies of hybrid CNC:CuO are explored. A novel approach for optimizing the thermophysical properties and heat transfer enhancement of low-volume concentrations of single and hybrid nanocoolants dispersed in EG base fluid is investigated in this research. The present study aims to evaluate the stability and thermophysical properties, heat transfer properties and investigate the optimum condition of the thermophysical properties of 0.01 vol % single CNC and CuO with its hybrid nanocoolant of 70:10, 80:20, and 90:10 of CNC to CuO. The nanocoolant's thermophysical properties were measured at temperatures ranging from 30°C to 90°C then were tested in a reduced-size radiator to evaluate their heat transfer performance under three varying volume flow rates of 0.75 LPM, 1.00 LPM and 1.25 LPM and working temperatures of 80 °C. The radiator's heat transfer coefficient, friction factor, Reynolds number, and Nusselts number are investigated. The curve fitting method and Response Surface Methodology (RSM) were used to predict the thermal conductivity, density, and specific heat. The visualization technique stability assessment confirmed that all the nanocoolants exhibited exceptional stability, as evidenced by the absence of sedimentation throughout the three-month period. The UV-Vis high value absorbance wavelength remained relatively constant during the four-week period, indicating the nanoparticle suspension is evenly distributed in the base fluid. The zeta potential of all hybrid nanocoolants demonstrates superior stability when compared to single nanocoolants, where CuO is unstable, and CNC exhibits moderate stability. These results confirm that the addition of CNC to CuO leads to a significant improvement in stability. The nanocoolant exhibits a significantly higher density at 100 °C, and the measured density closely corresponds to the theoretical value. The specific heat capacity decrease by increasing of temperature, the thermal conductivity showed a linear relationship with temperature, the kinematic viscosity decreased as the temperature increased. The Reynolds number exhibit direct relationshiop with the flow rate, Nusselt number increased with the increased of Reynolds number and volume concentrations. The maximum heat transfer coefficient occurred at 1.25 LPM for CuO and 80:20 nanocoolant, while the highest heat transfer enhancement of 79.88% was achieved by 80:20 at 0.75 LPM. The findings indicate that augmenting the volume flow rate of nanocoolant circulating through the radiator tubes leads to an improvement in both the heat transfer and the convective heat transfer coefficient. The experimental results showed that the heat transfer coefficient of the reduced-size radiator is significantly higher than that of the commercially sized radiator. Specifically, at flow rates of 0.75 LPM, 1.00 LPM, and 1.25 LPM, the heat transfer coefficient for the reduced-size radiator was observed to be greater by 51.21%, 89.99%, and 52%, respectively. RSM statistical modeling and optimizing the thermophysical parameters achieved exceptional results, with R2 values exceeding 80%, a P-value less than 0.05, and a difference between R2adj and R2pred of less than 0.2. This research advances the development of efficient, compact automotive cooling systems by utilizing low-volume concentration nanocoolants, highlighting the 80:20 CNC:CuO hybrid's effectiveness in enhancing thermal performance
ER  -