Duct loops and VAV modelling and control

This paper summarises the results of a now completed three year research programme into the modelling and control of variable air volume air conditioning. Three common VAV boxes, used in standard VAV and displacement ventilation systems, were analysed on a rig and new, more detailed, models developed compared to the current HVACSIM+ model. These models were then used to analyse duct loop systems. Although not extensively used in Europe, duct loop systems are shown to save up to 35% in fan power compared to conventional radial duct systems. Conventional, static pressure sensor positioning is briefly discussed and the saving from different positions shown from models of synchronous and asynchronous VAV systems. Stability and box authorities are also briefly discussed.