|Title:||Dynamic Modeling and Advanced Control of Air Conditioning and Refrigeration Systems
|Author(s):||Rasmussen, Bryan P.; Alleyne, Andrew G.
|Subject(s):||vapor compressor systems
|Abstract:||Over 15 billion dollars is spent on energy for residential air-conditioning alone each year, and air conditioning
remains the largest source of peak electrical demand. Improving the efficiency of these systems has the
potential for significant economic and environmental impact, but requires not only refining individual component
designs, but increasing overall system efficiency using advanced control strategies. Transient control of vapor
compression cycles faces two significant challenges: 1) creating control-oriented models that balance simplicity with
accuracy, and capture the complex heat and mass flow dynamics, and 2) developing control strategies that can
achieve high performance over a wide range of operating conditions.
This dissertation makes contributions on both fronts and can be divided into two distinct parts. The first
portion of the dissertation presents the development, simulation, and experimental validation of a first principles
modeling framework that captures the dynamics of a variety of vapor compression cycles in a form amenable to
controller design. These models are highly nonlinear, and require a nonlinear control strategy to attain high
performance over the entire operating envelope. To this end, a gain-scheduled control approach based on local
models and local controllers is presented that uses endogenous scheduling variables. This comprises the second
portion of the dissertation, where a theoretical framework for designing gain scheduled controllers, tools for
analyzing the stability of the nonlinear closed loop system, and experimental evaluation of advanced control
strategies for vapor compression systems is presented. These results demonstrate that while linear control techniques
offer significant advantages versus traditional a/c control systems over small ranges, the gain-scheduled approach
extends these advantages over the entire operating regime.
|Publisher:||Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
|Series/Report:||Air Conditioning and Refrigeration Center TR-244
|Sponsor:||Air Conditioning and Refrigeration Project 163
|Date Available in IDEALS:||2009-06-22