A dynamic mathematical model of a direct expansion (DX) water-cooled air-conditioning plant

A dynamic mathematical model for a direct expansion water-cooled air-conditioning plant typical to many actual installations in buildings has been developed. The system components modelled are a compressor, a thermostatic expansion valve, a water cooled condenser and a direct expansion evaporator which is also the cooling and dehumidifying coil in the air side. The evaporator (cooling coil) model consists of a novel set of equations which can distinguish between two-phase superheated and refrigerant region in the refrigerant side, and between dry and wet cooling of an air handling process in the air side. The model has been validated using the experimental data collected from the plant, and was separately reported.