Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator

摘要

This article present an experimental investigation of varied mass charges of Liquefied Petroleum Gas (40g, 50g, 60g and 70g) enhanced with varied TiO2 nanoparticle/mineral oil concentrations (0.2g/L, 0.4g/L and 0.6g/L nano-lubricants) in a R134a compressor of a domestic refrigerator. Performance tests investigated at steady state included: pull down time, power consumption, compressor power input, cooling capacity and coefficient of performance (COP). Analysis was based on temperature and pressure readings obtained from appropriate gauges attached to the test rig. Refrigerant property characteristics were obtained using Ref-Prop NIST 9.0 software. Results obtained showed almost equal evaporator air temperatures and reduction in power consumption for all tested nano-lubricant concentrations except at 70g charge of LPG using 0.6g/L nano-lubricant. Furthermore, the lowest compressor power input was found to be 21W and obtained using 70g of LPG with either of 0.2g/L or 0.4g/L nano-lubricants. At 70g of LPG using 0.6g/L concentration of nano-lubricant, highest cooling capacity index of 65W was obtained while the highest COP of 2.8 was obtained with 40g charge of LPG using 0.4g/L concentration of nanolubricant. In conclusion, LPG-TiO2 nano-lubricant mixture works safely and efficiently in domestic refrigerators without modification of capillary tube length, but requires adequate optimization.