Experimental performance evaluation for a carbon dioxide light commercial cooling application under transcritical and subcritical conditions

CO2 is one of the most interesting non toxic, nor flammable, low GWP natural fluid to be used in applications with a large direct contribution to global warming, such as vending machines. s paper the results of an experimental investigation on a small capacity, air-forced refrigerating plant working with CO2 are presented. The air inlet temperatures at gas cooler and evaporator were varied between 16 °C and 31 °C and between −25 °C and 25 °C, respectively, to cover the range of temperatures under conditions typical of commercial refrigeration, during quasi-steady operation. The thermodynamic analysis of the system performance was carried on varying independently the pressure at the gas cooler, by overfeeding the liquid receiver to point out the effect of refrigerant charge. sults allow to describe the performance of the system in a map varying the boundary conditions; at the same time the corresponding variations of the thermodynamic cycle, the COP and the mass flow rate are reported.