Energy and performance improvement of R32-based residential air conditioning using SiO2 and TiO2 nanolubricants

This study investigates how SiO 2 and TiO 2 nanoparticle additives improve the performance of a residential air conditioning system operating with R32 refrigerant and PVE lubricant. Improving energy efficiency in home cooling is important because air conditioners consume a large portion of global electricity. Nanolubricants were prepared using a two-step mixing method and tested in a modified R32 system. Testing followed ISO 5151 standard conditions at 35 °C, with performance also evaluated from 31 to 39 °C for comparison. The system performance was evaluated based on cooling capacity, mass flow rate, compressor work, power consumption, and overall efficiency under steady operating conditions. Results show that replacing the original working fluid with R32 reduces the refrigerant charge from 540 g to 350 g. The use of SiO 2 and TiO 2 nanolubricants reduced compressor work and increased mass flow rate, leading to better heat transfer and cooling output. The highest improvement was recorded at low additive concentrations. SiO 2 at 0.005 percent increased performance by up to 23 percent, while TiO 2 at 0.010 percent increased performance by up to 22 percent. Cooling capacity increased and power consumption decreased compared to pure PVE, enabling the system to deliver more cooling with less electricity. This study provides experimental data for a residential air conditioning system using R32 and PVE based nanolubricants, which has not been reported before. The results show that very small amounts of nanoparticles can improve system efficiency and reduce energy use under real operating conditions. Future work shall also include the study of PVE nanolubricant miscibility and the physical effects of nanoparticles on the compressor electrical motor.