Thermal Performance of Vapour Compression Refrigeration System using Bimetallic Strontium Hexaluminate Nanorefrigerants

Abstract

Nanoparticles are added to standard compressor lubricants to improve performance and reduce the energy consumption of vapour compression refrigeration systems (VCRS). This work evaluated the compatibility, viability, and utility of a bimetallic oxide strontium hexaluminate (SrAl12O19) nano-lubricant with nominal sizes of 20–40 nm by characterising and evaluating its thermophysical properties while assessing its effect on the performance and energy consumption of existing, unmodified VCRS. Eco-friendly R600a were used as the system's refrigerant and the performance, energy consumption, and energy efficiency of VCRS were investigated by altering the concentration of SrAl12O19 (1%–20%) in the compressor lubricant. The results showed that as the temperature increases, the viscosities significantly decreased and increased as the concentration of nanoparticles is increased. In contrast, the density and acidity of the nanolubricant increased as the volume concentration of nanoparticles increased. The addition of nanoparticles into the compressor oil enhanced the performance of the VCRS performance and reduced the energy required to operate the system; however, these performance metrics decreased as the concentration of nanoparticles increased further. When the concentration of nanoparticles increased, exergy efficiency reached the maximum at 5% volume concentration.