Performance of hydrocarbon refrigerants in a refrigerator with liquid line magnet and CNT nano-lubricant

The issues of flammability associated with A3-class hydrocarbon-based refrigerants are controllable by limiting their mass charges. However, these reductions in their mass charge below certain limits deteriorate their performance efficiency. In this experimental study, we analyzed the effects of a liquid line magnetic field (Mag), multi-wall carbon nanotube (CNT) nano-lubricant, and the combination of both (Mag-Nano) on the performance of a very low mass charge (i.e., 30 g) of R600a and LPG refrigerants, as a replacement to the 100 g R134a refrigerant in a domestic refrigeration system. The refrigerants were tested with and without CNT nano-lubricant (pure), two pairs of 3000 Gs liquid line mounted O ring N50 permanent magnets (Mag), 0.2 g/L concentration of CNT nano-lubricant (Nano), and in combination with a liquid line magnetic field and CNT nano-lubricant (Mag-Nano). The performance evaluation of the refrigerants includes the determination of coefficient of performance (COP), evaporator air temperature, volumetric refrigeration capacity, instantaneous power consumption, cumulative energy consumption, and energy cost. A reduction in the COP of R600a and LPG was observed to be about 11–42% and 14–26%, respectively, when compared to R134a. The R134a refrigerant had the lowest evaporator air temperature of −24.5 °C and the highest instantaneous power consumption of 74.6 W. The R600a-Mag-Nano refrigerant is the most efficient option, having the lowest instantaneous power consumption, energy cost, and cumulative energy consumption. The adoption of hydrocarbon refrigerants is more cost-effective than using the R134a refrigerant, resulting in a cost saving of about 8–26%. In conclusion, the proposed methods adopted to enhance the performance of refrigeration system, are very safe and effective.