Performance of multi-walled CNTs suspended with hydrocarbon refrigerant (R600a) and lubricating oil in vapour compression refrigeration system

Abstract

A single evaporator household refrigerator with a total volume of 70 L is used to evaluate multi-walled carbon nanotubes (CNTs) nanolubricant as a drop-in replacement for pure lubricant. Continuous running on the refrigerator is done with varying concentrations of multi-walled CNTs nanolubricant and different mass charges of R600a. The results show that using R600a with multi-walled CNTs nanolubricant concentration of 0.4 g/L to 0.6 g/L and a charge of 50 g to 60 g more result in a decreased pull downtime and evaporator temperature of -8 and -11 °C, respectively. Using 0.4 g/L multi-walled CNTs nanolubricant and 50 g of R600a, the lowest electric energy usage is attained. Higher refrigeration is attained with this combination. The pull-down time is lower and also the power consumption of the refrigerator is lower than those of pure lubricant in the refrigerator by about 25.9 %, 20.2 %, and 13.7 % for 50 g, 60 g, and 70 g, respectively, while using multi-walled CNTs nanolubricant of 04 g/L to 0.6 g/L. Finally, the proposed multi-walled CNTs nanolubricant appears to be a good choice for replacing pure lubricant in the refrigerator.