Study of a polymer ejector design and manufacturing approach for a mobile air conditioning

Polymer ejectors manufactured with injection molding offer a low cost and lightweight design for automotive applications compared to traditional metal designs. New materials need to be resistant against the refrigerant R1234yf and withstand the pressure under operating conditions of a mobile air conditioning. In this paper, a material research selects possible material candidates for a polymer ejector. A FEM simulation investigates the stability and deformation of the ejector when using a polymer material instead of the usual stainless steel solution. A selective laser sintering (SLS) printed polyamide 12 ejector is benchmarked in an enhanced vapor-compression refrigeration cycle against a stainless steel prototype on a test bench. Both ejectors implement the expected pressure levels and show a good pressure recovery rate. However, the new polyamide 12 ejector has a faster decrease of performance from its maximum efficiency. The difference in the ejector performance is expected to be caused by a larger manufacturing tolerance in the SLS printing, leading to a larger nozzle diameter. The design of a polymer ejector is successfully tested, offering new applications for the ejector technology in the automotive industry.