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The effect of compressor speed, initial refrigerant charge and volume concentrations of SiO2/PAG nanolubricant on the performance of automotive air-conditioning (AAC) system are investigated in this study. Response surface method (RSM) was used in designing the experimental work and is based on face composite design. The developed quadratic models from RSM were helpful to envisage the response parameters namely heat absorbs, compressor works, and coefficient of performance (COP) to identify the significant relations between the input factors and the responses. The results depicted that adding SiO2 nanoparticle into PAG lubricant will enhance the COP of AAC. Optimization of independent variables was performed using the desirability approach of the RSM with the goal of maximizing the heat absorb and COP, consequently, minimizing the compressor work. The results revealed that the optimal condition with a high desirability of 73.4% for the compressor speed of 900 rpm, refrigerant charge of 95 g and volume concentration of 0.07%. At this condition, the AAC system operated with 193.99, 23.28 kJ kg−1 and 8.27, respectively, for heat absorb, compressor work and COP. DoE based on RSM was capable of optimizing the significant parameters which affect AAC performance. [ABSTRACT FROM AUTHOR]

Lubrication is a requisite for any mechanical equipment that moved to avoid wear of sliding parts and enhance the equipment operation consistency. The objective of this study was to seek a new improved automotive air conditioning (AAC) compressor lubricant to enhanced AAC performances. The type of compressor is piston type, Sanden SD 7H10,that normally used by Malaysia compact car. The tribological investigation was focusing on Coefficient of friction and wear rate. The wear rate and coefficient of friction (COF) of Alumina/Polyalkylene glycol (Al2O3/PAG) nanolubricant were evaluated employing reciprocating test conditions to replicate a piston ring/cylinder liner contact following the ASTM G 181-11 Standard. Al2O3 nanoparticle was dispersed in PAG lubricant for volume concentrations between 0.006 to 0.014 vol %. Al2O3/PAG nanolubricant with 0.010 % vol. concentration showed the best reduction of frictional power loss. The enhancement of power saving due to frictional losses was up to 7.59 % compared to pure PAG lubricant. Furthermore, the wear rate of piston liner reduced by 33.39 %. Al2O3 nanoparticles in this circumstances, performed as a solid lubricant to reduce wear. These results show potential approach to enhance the AAC performance, save automotive fuel and elongated the life span for AAC compressor. [ABSTRACT FROM AUTHOR]

Ultrasonication is the act of applying sound force to agitate particles in a sample with the frequency of more than 20 kHz. It is an external vibration induced during preparation of nanolubricant that helps the particles to overcome the van der Waals force bonding. Nanolubricant prepared is intended to be used in automotive air conditioning (AAC) system to improve its performance. In this work, stability of Al2O3/Polyalkylene glycol (PAG) and SiO2/PAG nanolubricants of 0.2 % volume concentrations with different sonication time were investigated. Five samples for each nanolubricant were prepared by two-step method process with variation of sonication time from zero to two hours' time with half an hour interval. The stability tests were done by visual sedimentation and UV-vis spectrometer. The optimum sonication time found to be one and half hours and two hours for Al2O3/PAG and SiO2/PAG nanolubricants respectively. Both nanolubricants were found stable for more than two weeks' period. [ABSTRACT FROM AUTHOR]