A MOVING-BOUNDARY FORMULATION FOR MODELING TIME-DEPENDENT 2-PHASE FLOWS

A mathematical model describing the transient interactions in one-dimensional two-phase flows with heat transfer is presented. A moving-boundary refrigerant model is used to predict the position of the two-phase/vapor interface. A boundary immobilization technique is used to predict the temperature profile along the heat-exchanger wall. Typical results of an evaporator model, in terms of interface position and discharge superheat, are presented for inlet flow disturbances. The model is then used in an overall heat-pump simulation to predict cyclic performance. The results compare favorably to those obtained with a high-fidelity spatially dependent heat-pump model, but require significantly less computational effort.