Superheat control for air conditioning and refrigeration systems: Simulation and experiments

Otten, Richard J.

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https://hdl.handle.net/2142/16787 Copy

Description

Title

Superheat control for air conditioning and refrigeration systems: Simulation and experiments

Author(s)

Otten, Richard J.

Issue Date

2010-08-20T17:57:50Z

Director of Research (if dissertation) or Advisor (if thesis)

Alleyne, Andrew G.

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• control
• superheat
• air conditioning
• refrigeration
• Hardware in the Loop (HIL)
• load emulation
• feedforward
• schedule
• testing
• space model

Abstract

Ever since the invention of air conditioning and refrigeration in the late nineteenth century, there has been tremendous interest in increasing system efficiency to reduce the impact these systems have on global energy consumption. Efficiency improvements have been accomplished through component design, refrigerant design, and most recently control system design. The emergence of the electronic expansion valve and variable speed drives has made immense impacts on the ability to regulate system parameters, resulting in important strides towards efficiency improvement. This research presents tools and methodologies for model development and controller design for air conditioning and refrigeration systems. In this thesis, control-oriented nonlinear dynamic models are developed and validated with test data collected from a fully instrumented experimental system. These models enable the design of advanced control configurations which supplement the performance of the commonly used proportional-integral-derivative (PID) controller. Evaporator superheat is a key parameter considered in this research since precise control optimizes evaporator efficiency while protecting the system from component damage. The controllers developed in this thesis ultimately provide better transient and steady state performance which increases system efficiency through low superheat set point design. The developed controllers also address the classical performance versus robustness tradeoff through design which preserves transients while prolonging the lifetime of the electronic expansion valve. Another notable contribution of this thesis is the development of hardware-in-the-loop load emulation which provides a method to test component and software control loop performance. This method alleviates the costs associated with the current method of testing using environmental test chambers.

Graduation Semester

2010-08

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http://hdl.handle.net/2142/16787

Copyright and License Information

Copyright 2010 Richard James Otten. All rights reserved.

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