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Refrigeration Chiller Systems - Principles, Applications & Acceptance Testing

A. Bhatia, B.E.


Course Outline

A chiller is a refrigeration system that cools water. Once cooled, chilled water is used in air-conditioning applications for cooling/dehumidification and thus creating comfortable and productive environments. Chillers are also used in the manufacturing environment to provide process cooling to equipment in an effort to maximize productivity.

This 3-hr course material is based entirely on US Corps of Engineers Construction Engineering Research Laboratory (USACERL) technical report 99:20, May 1999. This course lists the Appendix C of the report.

The course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will:


Intended Audience

This course is aimed at beginners, novice engineers, building services design engineers, end users, service technicians, architects, maintenance supervisors, contractors, energy auditors, layout professionals and general audience.


Course Introduction

A chiller is a refrigeration system that cools a process fluid typically water, which in turn is used in commercial and industrial facilities for process cooling or air-conditioning. Water can be cooled to temperatures as low as 5°C (~40°F) and pumped through a hydraulic circuit to reach the process equipment or the air handling units. For still lower temperatures glycol or brine solution may be used.

A chiller will use either a vapor compression or absorption cycle to cool. There are four broad types of chillers (1) reciprocating, (2) centrifugal, (3) screw driven (4) and absorption chillers. The first three types are mechanical chillers which are powered by electric motors, steam, or gas turbines. Each of these chillers is a complete package comprising of a compressor, condenser, evaporator, expansion valve, refrigerant, internal piping and controls. The term Chiller is also used when all these components are used with cooling tower.

An absorption chiller is powered by a heat source such as steam and uses no moving parts.

Course Content

In this course, you are required to study the US Army Corps of Engineers Construction Engineering Research Laboratory (USACERL) technical report 99:20, May 1999 Appendix C.

US Army Corps of Engineers Construction Engineering Research Laboratory (USACERL) technical report 99:20 Appendix C


You need to open or download above document to study this course.

Course Summary

There are two basic types of chillers -- mechanical compression chillers and absorption chillers.

The mechanical compression cycle has four basic components through which the refrigerant passes: (1) the evaporator, (2) the compressor, (3) the condenser, and (4) the expansion valve. The evaporator operates at a low pressure (and low temperature) and the condenser operates at high pressure (and temperature).

The cycle begins in the evaporator where the liquid refrigerant flows over the evaporator tube bundle and evaporates, absorbing heat from the chilled water circulating through the tube bundle. The refrigerant vapor, which is somewhat cooler than the chilled water temperature, is drawn out of the evaporator by the compressor. The compressor "pumps" the refrigerant vapor to the condenser by raising the refrigerant pressure (and thus, the temperature). The refrigerant condenses on the cooling water coils of the condenser giving up its heat to the cooling water. The high-pressure liquid refrigerant from the condenser then passes through the expansion device that reduces the refrigerant pressure (and temperature) to that of the evaporator. The refrigerant again flows over the chilled water coils absorbing more heat and completing the cycle.

Mechanical compression chillers are generally classified by compressor type: reciprocating, centrifugal, and screw.

The absorption and the mechanical compression cycles have the evaporation and condensation of a refrigerant in common. In both cycles, the refrigerant evaporates at low pressure (and low temperature) to absorb heat and then condenses at higher pressure (and higher temperature) to reject heat to the atmosphere. Both cycles require energy to raise the temperature of the refrigerant for the heat rejection process. In the mechanical compression cycle, the energy is supplied in the form of work to the compressor whereas in the absorption cycle, heat is added (usually steam) to raise the refrigerant temperature.

The absorption cycle requires two working fluids: a refrigerant and an absorbent. Of the many combinations of refrigerant and absorbent that have been tried, only lithium bromide-water and ammonia-water cycles are commonly used today.

There are essentially three types of maintenance performed on chillers; water chemistry, mechanical maintenance and operational procedures. Water chemistry is maintained to keep proper balance and minimize the effects of scale, corrosion and micro-biological / debris fouling. Mechanical maintenance includes proper lubrication, adequate liquid refrigerant, oil levels and pump curve tests. Operational procedures include eddy-current tests, oil analysis, calibration of gauges and meters and other various tests.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz


DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.