Keywords: visi coolers, ternary mixture, propane, isobutane, R134a, performance characteristics, global warming, refrigerant mixtures, vapour compression refrigeration
Optimisation of visi cooler with the low global warming potential refrigerant mixture as an alternative to R134a and HC blend
In this study, the performance of a visi cooler has been evaluated by using the ternary mixture of R134a/R290/R600a with five different mass fractions as an alternative to R134a and HC mixture. Baseline tests have been carried out with R134a and HC mixture and the performance parameters were compared with the five selected alternative refrigerant mixtures. The performance is optimised by varying the refrigerant charge and capillary tube length under experimental conditions for both the pull-down test and the energy consumption test. The optimised refrigerant charge of the ternary mixture is approximately 50% of that of the optimised R134a system and the global warming effects will be decreased by two-thirds. The cooling speed is increased by 25% and COP is increased by 9.9%. The length of the capillary is increased by 63.63% to obtain the best performance. The agreement between the predicted values and experimental values is found to be satisfactory.