Consistent Initialization of System of Differential-Algebraic Equations for Dynamic Simulation of Centrifugal Chillers

For simulation of centrifugal chiller system with differential algebraic equations (DAEs), consistent initial conditions are difficult to obtain due to the two-phase refrigerant cycle and the connections between several components. Existing rigorous initialization methods are generally not easy to apply and not suitable for the particular problem of centrifugal chiller simulation, such as the surge avoidance. In this paper, the transient model of a water-cooled centrifugal chiller is developed in Modelica with Dymola and the TLK/IfT Library (TIL). A new preprocessing scheme and a direct initialization method are proposed for the consistent initialization for centrifugal chiller. Simulation results have shown the effectiveness of the proposed modeling framework and the initialization method.