Absorption Chillers

Course Number: 440

This course covers the basic principles of absorption refrigeration as compared to mechanical refrigeration. It introduces absorption terminology and common absorption fluid pairs. It examines water/lithium bromide systems, ammonia/water systems, and evolving systems, and concludes with a discussion of chiller selection factors, cost of operation, and absorption system applications.

Recommended Contact Hours - 12

Chapter 1: Principles of Absorption Chiller Systems

Topics: Mechanical vs. absorption refrigeration systems; Absorption terminology; Single-effect absorption cooling; Common absorption fluid pairs

Learning Objectives:

• Explain the differences between a mechanical refrigeration system and an absorption system.
• Describe the basic components in a simple absorption system and their functions in the refrigeration cycle.
• Distinguish between the characteristics of a weak solution and a strong solution and explain the function of each in the absorption cycle.
• Define the terminology associated with absorption systems.
• Describe the steps in a simple single-effect absorption cooling cycle.

Chapter 2: Water/Lithium Bromide Absorption Systems

Topics: Water/lithium bromide systems; Double-effect direct-fired system; Solution flow cycles; Operating characteristics; Crystallization

Learning Objectives:

• Discuss basic characteristics of water/lithium bromide absorption systems and name common industrial uses.
• Describe the differences between single-effect and double-effect absorption systems.
• Discuss the action of the solution and the refrigerant throughout a solution cycle within absorption systems used for heating only, cooling only, and simultaneous heating and cooling.
• Compare reverse, series, and parallel solution flow cycles.
• Discuss operating characteristics of various absorption machines and explain how the coefficient of performance (COP) is used in equipment selection.
• Describe the cause of crystallization and its effect on an absorption system.

Chapter 3: Lithium Bromide Absorption

Topics: Controls and Maintenance - Limitations; Control scheme; Start, run, and shut down sequence; Operating limits; Safety controls; Maintenance; Insulation; Noncondensables gases

Learning Objectives:

• Discuss the general operating limits of absorption units, including ASHRAE 15 machine room safety requirements.
• Describe the basics and benefits of today's microprocessor-based operation and capacity control.
• Describe the normal absorption unit start, run, and shutdown sequences.
• Name various kinds of system operating controls and safety controls and explain their functions.
• Describe general setup and maintenance requirements and the procedures that keep the absorption chiller operating efficiently.
• Discuss the necessity for insulation and control of noncondensable gases, including air.

Chapter 4: Ammonia/Water Absorption Systems

Topics: Ammonia systems background and characteristics; Basic, industrial, and domestic ammonia/water absorption systems; Ammonia system advantages

Learning Objectives:

• Discuss the solubility of ammonia in water and other characteristics, including hazards, that affect ammonia absorption systems.
• Explain the function of the analyzer and rectifier in an ammonia absorption system.
• Define the terms strong aqua and weak aqua as related to the ammonia water solution and compare them with the terms strong solution and weak solution as related to a lithium bromide system.
• Describe typical applications for industrial ammonia absorption systems and small residential and commercial ammonia absorption systems.
• Explain the operation of the Platen-Munters ammonia/water/hydrogen system.
• Name reasons why ammonia absorption systems are likely to be used increasingly in the future.

Chapter 5: Evolving Absorption Systems

Topics: Improving COPs; GAX heat pump cycles; Triple-effect cycles; Single-effect system with heat recovery; Double-effect system with solar heating; Power plant heat recovery; Hybrid high-lift pump with mechanical compression

Learning Objectives:

• Discuss reasons for continuing testing and development of advanced absorption systems.
• Describe current developments in the GAX ammonia/water residential heat pump systems.
• Describe triple-effect systems and compare absorption and adsorption cycles.
• Explain how special-application absorption systems use recovered heat, waste heat, or a solar array to provide the energy for operation.
• Describe the properties of non-standard solution pairs.
• Explain how two kinds of hybrid arrangements incorporate the absorption system.

Chapter 6: Absorption vs. Mechanical Compression Systems

Topics: Water/lithium bromide, ammonia/water absorption units; Mechanical compression systems; Chiller selection factors; Economic perspectives; Absorption system application

Learning Objectives:

• Describe important characteristics of both single-effect and double-effect water/lithium bromide absorption chillers and ammonia/water absorption units.
• Briefly describe the operation and characteristics of centrifugal chillers.
• Briefly describe the operation and characteristics of reciprocating and screw positive-displacement chillers.
• Name factors that must be considered in selecting air-conditioning equipment for specific applications and compare COPs for the various kinds of equipment.
• Discuss general cost criteria for the various types of energy used to drive the equipment and describe an appropriate absorption system application.