Experimental investigation of a vapour compression refrigeration system using R134a/Nano-oil mixture

•Analysis of a vapour compression refrigeration system was carried out using nano-oil.•Al2O3 nanoparticles were chosen for preparing the nano-oil.•COP of the system improved by as much as 6.5 % due to nano-oil.•Nano-oil enhanced the degree of subcooling in the condenser. The current research is focused on the application of nanoparticles in vapour compression refrigeration systems. The major aim of the study is to investigate the effects of nano-oil on various performance parameters of the vapour compression refrigeration systems such as refrigeration capacity, compressor power, compressor discharge temperature and last but not the least, the coefficient of performance (COP) of the refrigeration system. Nano-oil was prepared by dispersing Al2O3 nanoparticles in PAG oil. Al2O3 nanoparticles were chosen because of aluminium oxide's superior thermophysical properties and a low dielectric constant in comparison to other commonly used nanoparticles such as CuO and TiO2. The above-mentioned performance parameters were compared for broadly two different cases, viz., VCRS working on R134a/PAG mixture and VCRS working on R134a/PAG/Al2O3 (R134a/nano-oil) mixture. The system analysis was conducted at several evaporator temperatures ranging from -11 °C to 1 °C and at two different condenser temperatures, viz., 30 °C and 34 °C. The dispersion of nanoparticles into the compressor oil resulted in a higher degree of subcooling at the condenser exit. It was also found that the COP of the system increased by as much as 6.5 % due to the addition of nanoparticles in the system.