Exploration of control strategies for air side design in active chilled beams

Abstract

Heating Ventilating and Air Conditioning systems can consume up to 30% of the

overall energy consumed by a building. Profound emphasis is being laid on

constructing green buildings conforming to Greenmark and LEED certifications or

making the existing building more energy efficient. Energy savings by making

HV AC systems more efficient has become feasible since the advent of Active

Chilled Beams which have become a popular alternative to generic VA V systems

over the recent years due to their energy saving potential and minimal space

requirements.

The physical design characteristics of chilled beams cannot be credited entirely for

operational efficiencies and low power consumption in HV AC systems. Without the

assistance of high and low level, robust and stable control system it is difficult to

maintain the desired thermal load with acceptable levels of operational efficiencies.

This master's thesis aims to explore multiple control strategies for air side design

utilizing active chilled beams. The air side design considerations include the control

of fan that supplies the primary air to the duct and a damper that controls the air-flow

rate to the ACB terminal unit. A model of the system has been developed using an

intelligent identification algorithm based on empirical system modelling established

on the method of linear least squares. A comparison of controller and system

performance was conducted on a pilot plant between PID controller using Internal

Model Control structure and Generalized Predictive Controller based N-Star tuning

algorithm and the latter has shown promising performance than a PID controller by

displaying less overshoot, faster settling time and better robustness.