A Low-Order Model for Nonlinear Dynamics of Heat Exchangers


This paper proposes a novel low-order heat exchanger modeling approach that possesses the merits of both lumped parameter and moving boundary methods. The dynamics of refrigerant flow are described by the total mass and energy balances across the entire heat exchanger, and the phase transition boundaries are determined by assuming a linear or exponential profile of refrigerant enthalpy distribution. An improved LMTD method is developed to handle temperature crossing. Airside heat transfer is calculated based on a row-by-row analysis. The presented approach owns invariant model structure, resulting in superior numerical robustness. A direct comparison of the proposed model with finite volume and moving boundary methods demonstrates significant improvement over computational speed while the physical integrity is still preserved.