Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 92, Issue 1 (2022) 9-17 9 Journal of Advanced Research in Fluid Mechanics and Thermal Sciences Journal homepage: https://semarakilmu.com.my/journals/index.php/fluid_mechanics_thermal_sciences/index ISSN: 2811-3950 Experimental Investigation on Newtonian Behaviour and Viscosity of TiO 2 /PVE Nanolubricants for Application in Refrigeration System Mohd Farid Ismail 1,2 , Wan Hamzah Azmi 1,3,* , Rizalman Mamat 1 , Abdul Hamid. Hamisa 1,4 1 Department of Mechanical Engineering, College of Engineering, Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300 Gambang, Kuantan, Pahang, Malaysia 2 Faculty of Mechanical and Manufacturing Engineering Technology, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya 75150, Durian Tunggal, Melaka, Malaysia 3 Centre of Excellence for Advanced Research in Fluid Flow, Lebuhraya Tun Razak, 26300 Gambang, Kuantan, Pahang, Malaysia 4 School of Engineering, Faculty of Science, Engineering and Agrotechnology, University College of Yayasan Pahang (UCYP), Taman Gelora, Jln Dato’ Abdullah, 25050 Kuantan, Pahang, Malaysia ARTICLE INFO ABSTRACT Article history: Received 3 October 2021 Received in revised form 21 December 2021 Accepted 3 January 2022 Available online 29 January 2022 The flow characteristics are highly dependent to viscosity of the fluid. For nanolubricant with different concentration, viscosity change is one of important parameter to be measured to evaluate its functional ability as lubricant. This paper studies about the effect of TiO2 nanoparticle in poly vinyl ether (PVE) at different concentration and temperature. Nanolubricant with volume concentration between 0.01% to 0.1% prepared using two-step method and tested at 40°C, 60°C, and 80°C temperature by using digital rheometer. Beforehand, the colloidal suspension fluid was observed by visual and zeta potential measurement to ensure its stability. The fluid Newtonian behaviour was identified for shear rate up to 1000 rpm. The results shown that dynamic viscosity of 0.01% TiO2/PVE nanolubricant had decreased up to 11% for all measured temperature. For other samples, viscosity increment does not reach more than 1.5% compared to pure PVE oil. It also observed that viscosity increment by the increasing of volume concentration, but it decreases by the increment of temperature. The finding in this study confirms that viscosity of TiO2/PVE nanolubricant effected by both temperature and volume concentration to opposite behaviour. Keywords: Compressor lubricant; refrigeration; rheology property; poly vinyl ether; Newtonian fluid 1. Introduction Viscosity property for compressor lubricant in refrigeration system shall be under its limit so that the system can runs properly. As the compressor lubricant being compressed together with refrigerant in the cycle, lubricant will be forced to change its viscosity depending on temperature at the specific component or area [1]. For instance, inside the compressor the temperature is high that can be reach up to 100°C. At this moment, high viscosity lubricant is required to ensure the compressor remain wet with lubricant for a good tribological affect. However, as usual lubricant viscosity will decrease by the increasing of temperature [2]. With high pressure produced by * Corresponding author. E-mail address: wanazmi2010@gmail.com https://doi.org/10.37934/arfmts.92.1.917