Investigation of residential air conditioning performance using TIO2/PVE, SIO2/pve, and their hybrid nanolubricants /
Safril,
Investigation of residential air conditioning performance using TIO2/PVE, SIO2/pve, and their hybrid nanolubricants / Safril - xvi, 285 pages : illustration ; 30 cm. + 1 CD-ROM.
Faculty of Mechanical and Automotive Engineering Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang - 2025
Includes bibliographical references
The market demand for high-performance and sustainable residential air conditioning (RAC) systems is growing. One approach to saving energy and improving the performance of RAC is dispersing nanoparticles into pure lubricants; however, the exploration is limited to the variation of volume concentration and experimental system. This study aims to observe the thermo-physical and tribological properties by utilizing TiO2 and SiO2 nanoparticle dispersion into polyvinyl ether (PVE) lubricants, investigate the performance of hybrid nanolubricants operated at different binary ratios, and optimize the binary ratio at optimum conditions. A two-step method was used to prepare hybrid nanolubricants with a volume concentration of 0.0043%. The variations of the binary ratio of TiO2-SiO2/PVE hybrid nanolubricant were undertaken for TiO2 (100%), SiO2 (100%), 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, and 90:10. Quantitative and qualitative methods were used to evaluate the stability of the hybrid nanolubricant. Thermo-physical observations for thermal conductivity and dynamic viscosity were measured at 30 °C and up to 100 °C. ASTM D4172 standard was used to investigate the tribological properties of a hybrid nanolubricant. The experimental performance of the RAC system was conducted on the RAC test rig, which was adjusted with a thermal control room and temperature operated according to MS1525:2014 standard recommendation. Optimization utilized the response surface method (RSM) approach, which utilized face composite design (FCD) function and analysis of variance (ANOVA). Binary ratio, compressor speed, and volume concentration were used as input parameters to optimize the RAC system. The samples of hybrid nanolubricant for all binary ratios were observed in good stability conditions with an absorbance ratio of more than 62% for 30 days of UV-Vis evaluation and with excellent zeta potential of more than 60 mV. The thermal conductivity of hybrid nanolubricants was improved to a higher level than that of PVE lubricants for all operating conditions. At a temperature of 60 ℃, the highest thermal conductivity enhancement of 4.2% was achieved by a 60:40 binary ratio, compared to other binary ratios, which experienced an increase in thermal conductivity of 3.29%. The dynamic viscosity trend of the hybrid nanolubricant showed a Newtonian behaviour similar to PVE lubricant and experienced a maximum increase of 15.83%. However, some samples experienced lower dynamic viscosity than pure PVE lubricant at a temperature of 80 to 100 ℃. Interestingly, the permittivity of the hybrid nanolubricant increased significantly by up to 88.6% for a 50:50 binary ratio, higher than that of the PVE lubricant, and it is helpful for electrical environment lubrication. The results of the tribology investigation were satisfactory, where the coefficient of friction (CoF) reduction almost occurred in all samples except for the 80:20 binary ratio. Specifically, the binary ratios of 0:100 and 60:40 showed significant CoF reductions of 17.60% and 11.09%, respectively, and similar results showed wear scar diameter (WSD) reductions of 47.09% and 40.11%, respectively. Finally, the experimental results for hybrid nanolubricant performance were summarized with a reduction in compressor work, improvement in coefficient of performance and cooling capacity, and reduction in power consumption, respectively, of 4.77%, 6.90%, 6.45%, and 1.82% at a 70:30 binary ratio. This finding was supported by the RSM optimization, which suggested a 68.83:31.17 optimum binary ratio, with the response parameters of cooling capacity, compressor work, power consumption, and evaporation discharge, respectively, of 2.54 kW, 47.62 kJ/kg, 0.94 kW, and 18.68 °C, with an overall desirability of 0.886. In conclusion, the TiO2-SiO2/PVE nanolubricant operated with R32 positively improved the RAC performance, and the optimum binary ratio of 68.83:31.17 was recommended for further application in the actual RAC system.
THE0010335 (Local)
Faculty of Mechanical and Automotive Engineering Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations
Investigation of residential air conditioning performance using TIO2/PVE, SIO2/pve, and their hybrid nanolubricants / Safril - xvi, 285 pages : illustration ; 30 cm. + 1 CD-ROM.
Faculty of Mechanical and Automotive Engineering Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang - 2025
Includes bibliographical references
The market demand for high-performance and sustainable residential air conditioning (RAC) systems is growing. One approach to saving energy and improving the performance of RAC is dispersing nanoparticles into pure lubricants; however, the exploration is limited to the variation of volume concentration and experimental system. This study aims to observe the thermo-physical and tribological properties by utilizing TiO2 and SiO2 nanoparticle dispersion into polyvinyl ether (PVE) lubricants, investigate the performance of hybrid nanolubricants operated at different binary ratios, and optimize the binary ratio at optimum conditions. A two-step method was used to prepare hybrid nanolubricants with a volume concentration of 0.0043%. The variations of the binary ratio of TiO2-SiO2/PVE hybrid nanolubricant were undertaken for TiO2 (100%), SiO2 (100%), 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, and 90:10. Quantitative and qualitative methods were used to evaluate the stability of the hybrid nanolubricant. Thermo-physical observations for thermal conductivity and dynamic viscosity were measured at 30 °C and up to 100 °C. ASTM D4172 standard was used to investigate the tribological properties of a hybrid nanolubricant. The experimental performance of the RAC system was conducted on the RAC test rig, which was adjusted with a thermal control room and temperature operated according to MS1525:2014 standard recommendation. Optimization utilized the response surface method (RSM) approach, which utilized face composite design (FCD) function and analysis of variance (ANOVA). Binary ratio, compressor speed, and volume concentration were used as input parameters to optimize the RAC system. The samples of hybrid nanolubricant for all binary ratios were observed in good stability conditions with an absorbance ratio of more than 62% for 30 days of UV-Vis evaluation and with excellent zeta potential of more than 60 mV. The thermal conductivity of hybrid nanolubricants was improved to a higher level than that of PVE lubricants for all operating conditions. At a temperature of 60 ℃, the highest thermal conductivity enhancement of 4.2% was achieved by a 60:40 binary ratio, compared to other binary ratios, which experienced an increase in thermal conductivity of 3.29%. The dynamic viscosity trend of the hybrid nanolubricant showed a Newtonian behaviour similar to PVE lubricant and experienced a maximum increase of 15.83%. However, some samples experienced lower dynamic viscosity than pure PVE lubricant at a temperature of 80 to 100 ℃. Interestingly, the permittivity of the hybrid nanolubricant increased significantly by up to 88.6% for a 50:50 binary ratio, higher than that of the PVE lubricant, and it is helpful for electrical environment lubrication. The results of the tribology investigation were satisfactory, where the coefficient of friction (CoF) reduction almost occurred in all samples except for the 80:20 binary ratio. Specifically, the binary ratios of 0:100 and 60:40 showed significant CoF reductions of 17.60% and 11.09%, respectively, and similar results showed wear scar diameter (WSD) reductions of 47.09% and 40.11%, respectively. Finally, the experimental results for hybrid nanolubricant performance were summarized with a reduction in compressor work, improvement in coefficient of performance and cooling capacity, and reduction in power consumption, respectively, of 4.77%, 6.90%, 6.45%, and 1.82% at a 70:30 binary ratio. This finding was supported by the RSM optimization, which suggested a 68.83:31.17 optimum binary ratio, with the response parameters of cooling capacity, compressor work, power consumption, and evaporation discharge, respectively, of 2.54 kW, 47.62 kJ/kg, 0.94 kW, and 18.68 °C, with an overall desirability of 0.886. In conclusion, the TiO2-SiO2/PVE nanolubricant operated with R32 positively improved the RAC performance, and the optimum binary ratio of 68.83:31.17 was recommended for further application in the actual RAC system.
THE0010335 (Local)
Faculty of Mechanical and Automotive Engineering Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations