Search

Vapor compression cycle systems using accumulators and receivers inherently operate at or near a transition point involving changes of phase at the heat exchanger outlets. This work introduces a condenser/receiver model and an evaporator/accumulator model developed in the moving-boundary framework. These models use a novel extension of physical variable definitions to account for variations in refrigerant exit phase. System-level model validation results, which demonstrate the validity of the new models, are presented. The model accuracy is improved by recognizing the sensitivity of the models to refrigerant mass flow rate. The approach developed and the validated models provide a valuable tool for dynamic analysis and control design for vapor compression cycle systems. [ABSTRACT FROM AUTHOR]

The article reports on implicit quasi-steady-state approximation and application to a power plant evaporator. The construction of reduced order models using quasi-steady-state or singular perturbation approach can hardly offer good low frequency approximations. An implicit quasi-steady-state technique is planned for general nonlinear models. The resulting reduced order model is exact to first order in the perturbation parameter and its linearization is correct to first order in frequency.