Adverse effects of compressor lubricant on household refrigerator-freezer performance and sustainable, feasible remedies

This study reviews the impact of lubricants on the components and efficiency of household refrigerator-freezers (HRFs). A comprehensive review of the existing literature reveals that lubricants impair overall heat transfer performance within heat exchangers while simultaneously increasing the overall frictional pressure drop. Additionally, the presence of oil disrupts the refrigerant flashing process within the capillary tube and reduces both the cooling capacity and the coefficient of performance of the system. This leads to increased compressor power consumption to achieve the same cooling capacity. Consequently, despite the potential of oil to decrease discharge temperature and mitigate seal leakage losses, it negatively impacts overall system performance. To counter these adverse effects, this study presents three strategies, derived from an extensive review: the use of oil-free compressors, the incorporation of nanoscale additives, and the application of oil separators. The review suggests that nanoscale additives, provided they are uniformly dispersed throughout the refrigerant and oil over a prolonged period, hold promise in enhancing heat transfer performance and mitigating the degradation caused by oil. Oil-free compressors also show considerable potential, though challenges associated with increased noise and reduced lifespan due to the absence of oil remain. The use of oil separators in HRFs is a relatively under-investigated topic, with fewer studies compared to the other two strategies, indicating the need for further research. This underscores the importance of continued study in this field to optimize the performance and efficiency of HRFs.