Energy and exergy analysis of vapour compression test rig using R134a blended with GN- MWCNT/POE hybrid nano-lubricants

Abstract

ABSTRACT The most common refrigeration system is the vapor compression refrigeration (VCR) system for a household refrigerator. The challenges for researchers are to minimize the power consumption of the compressor to improve the performance of the refrigeration system. This study aimed to assess and compare the energy and exergy analysis of VCR systems using multi-walled carbon nanotubes (MWCNT) and graphene nanosheets (GN) based hybrid nano-lubricants. The mass concentrations of each nanoparticle 0.3 g/L, 0.5 g/L, 0.7 g/L, and 0.9 g/L are mixed with 250 ml of polyolester oil (POE) separately and charged with 200 g of R134a refrigerant. Furthermore, the MWCNT and GN nanoparticles are mixed in a 50:50 proportion to prepare the same concentration of hybrid nanoparticles. The properties of refrigerants are obtained with the help of REFPROP 9.1 software. The pull-down time, compressor power, pressure ratio, exergy loss, relative irreversibility (RI), and second law efficiency (SLE) are variables that have been examined. The mass concentration of 0.7 g/L of hybrid nano-lubricants (GN-MWCNT/POE) is found to be optimal. It is noted that the pull-down time, power consumption, and pressure ratio of the refrigerator are lowered by 9.01%, 16.09%, and 5.68% respectively when compared to the pure refrigerant, whereas the actual COP and SLE improved by 11.29% and 8.22% at 0.7 g/L hybrid nano-lubricants. In addition, exergy loss and relative irreversibility are decreased for hybrid nano-lubricants.