Development of reduced-order modeling of a multiphase flow in an ejector

Ejectors in a vapor compression system recover expansion losses to increase the compressor suction pressure and decrease the total work input to the cycle. This is accomplished by entraining low-pressure vapor from the evaporator using a high-pressure liquid jet accelerated through a converging nozzle. In this context, cycle models of different fidelities are employed to investigate performance and optimize operation. Currently, ejector component models or submodels are primarily empirically closed with efficiency and flow coefficient values either adopted from literature or obtained experimentally. However, these approaches limit their broader applicability to other fluids of interest. There is a need for a non-empirical approach based on an understanding of ejector physics that can be used to model all refrigerants, requiring only already-known refrigerant properties as inputs, such as those existing in the National Institute of Standards and Technology (NIST) database. This work considers details of ejector physics and develops submodel closures that can be used to generalize ejector submodels for all refrigerants. A particular focus is on determining a minimally sufficient set of refrigerant properties from the NIST database that are required as inputs. This presentation provides a high-level overview of the ongoing work to generalize ejector submodels for refrigeration cycle modeling.