Abstract
A dynamic cycle simulation model of a multi-split type electric air-conditioning system for buildings is developed. The target air-conditioning system is an air-source heat pump system using a vapor compression cycle and composed of multiple indoor and outdoor units. The developed model consists of performance characteristics of components, digital feedback control algorithm, constraint for refrigerant charge amount, and connecting and boundary conditions. For the refrigerant side of the components with long transit times, dynamic balance equations for mass, momentum, and energy are formulated. Static balance equations are applied to the components with short transit times. The model results in nonlinear differential algebraic equations, which are solved by our hierarchical combination of the Runge-Kutta and Newton-Raphson methods. Then, the dynamic behavior to stepwise changes in the set points of the operation controls in the target air-conditioning system, i.e., the set points of the compressor inlet and outlet pressures and the air flow rate of the outdoor unit fan, is analyzed for the development of an active operational management approach.
