Exergetic analysis of low gram nano-refrigerant charge for transport application

Limited gram charge is beneficial in transport refrigeration by sustenance of flammability limits for safety. Herein, an experimental investigation of 0.11 vol. % of titanium IV oxide doped with 30 g each of R600a and LPG as R6_ooaAl2O3 and LPG_Al2O3 nano-refrigerants were retrofitted into a 102g R134a vapour compression refrigerating system. At steady state, the performance of the system using unblended R134a, R600a, LPG refrigerants, R600a_Al2O3 and LPG_Al2O3 nano-refrigerants were examined as a function air evaporator temperature and compressor characteristics; discharge pressure, power consumption, compressor exergetic defect, coefficient of performance and exergetic efficiency. At 80g charge, R600a, LPG, R6_ooaAl2O3 and LPG_Al2O3 had higher COP; Exergetic efficiency; but lower Total exergetic defect of  2.9, 11.3, 9.7 and 14.1%; 19.4, 22.1, 31.8 and 29.4%; and 34.1, 43.6, 56.3 and 58.6% than R134a. R134a has higher discharge pressure of 0.25, 0.12, 0.77 and 0.84 Psia/ 0.77, 0.12, 0.84 and 0.25 Psia; higher power consumption of 14.79, 12.23, 27.83 and 26.51 Watts; higher compressor exergetic defect of 0.03, 0.03, 0.06 and 0.04 Joule, lower coefficient of performance of 0.06, 0.23, 0.71 and 1.18; and lower exergetic efficiency of 0.012, 0.008, 0.056, 0.062 Joule than R600a, LPG, R6_ooaAl2O3, LPG_Al2O3. motor compression work of unblended R134a refrigerant is higher than unblended R600a, unblended LPGAl₂O₃ blended in R600a and LPG by 15.28%, 16.08%, 37.73% and 40.43. All the selected refrigerants met the chill compartment temperature, ISO 8187 compartment standard of -2 ≤ tcc min, max ≤ +3, while R6_ooaAl2O3 and LPG _Al2O3 nano-refrigerants showed improved compressor characteristics.