A novel R744 multi-temperature cycle for refrigerated transport applications with low-temperature ejector: experimental ejector characterization and thermodynamic cycle assessment

A novel vapor-compression system concept employing carbon dioxide as the refrigerant is proposed to serve needs of a typical medium-size refrigerated truck used for multi-temperature (MT and LT) goods delivery. The design based on implementation an ejector only component increasing pressure from LT evaporation MT pressure, thus providing cooling effect at two different temperature levels with one stage compression. was experimentally tested its ability effectively entrain mass flow rate low suction conditions (corresponding -25°C) assessed. Lower external ambient temperatures consequent lower expansion energy available motive nozzle leads reduction maximum achievable lift. Moreover, significant degradation performance towards highest lifts experienced. Based experimental data, numerical evaluation unit has been performed, highlighting that in (LT provides freezing power ranging between 1.1 kW 2.3 corresponding minimum 5.1 3.8 kW, depending chosen can be further increased by compressor rate. COP maximized lift provided ejector.