Modeling of vapor compression cycles for advanced controls in HVAC systems

This paper presents a new lumped-parameter model for describing the dynamics of vapor compression cycles. In particular, the dynamics associated with the two heat exchangers, i.e. the evaporator and the condenser, are modeled based on a moving-interface approach by which the position of the two-phase/single-phase interface inside the one-dimensional heat exchanger can be properly predicted. This model relates critical performance outputs, such as evaporating pressure, condensing pressure, and superheat, to actuating inputs including compressor speed, fan speed, and expansion valve opening. In view of regulating multiple performance outputs in modern heat pumps and air conditioning systems, this model is highly useful for the design of multivariable feedback control.