THERMAL COMFORT LEVELS AND ENERGY EFFICIENCY: STUDIES WITH AN INTEGRATED CONTROL SYSTEM

Abstract

The dissertation concerns the design of controllers for Variable Air Volume (VAV) system by manipulating flow rate of air in order to control the air temperature of a room. It explains clearly the steps of controller design from the application of the First Law of Thermodynamics, concerning energy balance of heat in the chamber, to the usage of Quarter Decay Ratio Tuning Formula . It also introduces the technique of auto-tuning. The evaluation of the total performance of the system is done in terms of controllability, thermal comfort and power consumption. It is observed that Proportional plus Integral (PI) mode reduces offset which appears in Proportional (P) mode, but it consumes more power. Both controllers have good response time, meaning that they can bring back the room air temperature into the throttling range fast. The area which is close to the return air diffuser experiences the warmest sensation and the one which is at the center of the room experiences the coolest one.