A transient model of a two-zone variable-air-volume system was developed. The system consists of two environmental zones, a cooling and dehumidifying coil, a chiller and storage tank, a fan, and a ductwork system. A total of 328 nonlinear time-varying equations were used to describe the dynamics of the VAV system. Nine control inputs to the system (six dampers, fan and chiller energy inputs, and mass flow rate of chilled water) can be varied to study their effects on zone temperatures, humidity ratios, supply air conditions, mass flow rates, fan speed, chilled-water temperature, outdoor air flow rates, and mixed air conditions. The disturbances acting on the system are those due to variations in outdoor temperature, sensible and latent loads on the zones, plenum temperature, and the temperature of the water returning from the cooling tower. Results are given showing the open-loop responses of the system subject to the constant inputs and disturbances cited.

KEYWORDS: variable volume air conditioning, models, calculating, zones, temperature, air flow rate, humidity, coefficient of performance, controls, air distribution, thermodynamics