Intermediate Ammonia Refrigeration Systems

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Course Overview

During this course, you will expand your understanding of the equipment used in ammonia refrigeration systems and learn application-specific tips.

Who Should Attend?

  • Refrigeration system operators 
  • Plant, facilities, application, and design engineers 
  • Ammonia refrigeration contractors 
  • PSM Coordinators wanting to learn more about the technology 
  • Sales and engineering staff with refrigeration equipment manufacturers

Additional Information

Note: Participants are expected to have completed the Introduction to Ammonia Refrigeration Systems course or have significant work experience with refrigeration systems.

This course is part of the Process Safety Management Professional Certificate. Increase your knowledge and effectiveness at managing PSM/RMP programs for your ammonia refrigerated facility, while earning a recognized credential. This course can be taken individually as well.

Course Outline

Day 1

Workshop Introduction 
Refrigeration Systems Review 

  • Introduction to types of systems: direct expansion, flooded, liquid overfeed
  • System components and arrangements
  • Refrigerant selection criteria

Properties of Ammonia Refrigerants 

  • Fundamental properties: pressure, volume, temperature
  • Derived properties: enthalpy, internal energy, transport
  • Phase change
  • Diagrams: pressure vs. enthalpy, pressure vs. temperature
  • Refrigerant comparison: Fluorochemicals, ammonia, water, CO2
  • Flash gas
  • Subcooling and superheat
  • Influence of water in ammonia refrigerant properties

Psychrometric Properties and Processes

  • Definitions: dry bulb, wet bulb temperatures, humidity ratio, psychrometric chart
  • Psychrometric processes: latent and sensible energy changes
  • Effects of refrigerant evaporating temperature on space humidity levels

Property Workshop

Psychrometric Properties and Processes (continued)

Refrigeration Load Calculations

  • Temperature requirements
  • Loads: envelope, product, other internal heat gains
  • Evaporator fan heat gains
  • Make-up air loads
  • Door loads - theory vs. real-world


Day 2

Refrigeration Cycles and Cycle Performance

  • Conservation principles
  • Performance measures
  • Capacity and required refrigerant mass flow rates
  • Overview of multi-stage systems

Compressors and Compressor Performance

  • Interpreting compressor maps
  • Correcting for actual compressor application/operation
  • Compression ratio limits
  • Part-load and off-design operation
  • Oil cooler heat rejection methods (screw compressors)
  • Economized ratings - when to/not to use (screw compressors)

Compressor Workshop

Vessels and Refrigerant Pumps

  • Types: high-pressure receiver, low-pressure accumulator, flash intercooler
  • Configurations: horizontal or vertical
  • Ratings
  • Proper practices for system integration
  • Knock-out velocity and down-comer sizing
  • Pump types and performance curves
  • Net positive suction head available vs. required
  • Refrigerant pump cavitation (causes and cures)


Day 3


  • Types
  • Performance characteristics and ratings
  • Selection and operation
  • Configuration: top feed or bottom feed
  • Defrosting techniques
  • Effects of pressure regulators
  • Determining optimum refrigerant feed rates (overfeed systems)

Condensers and Heat Recovery

  • System Types
  • Performance characteristics
  • Selection
  • Heat recovery potential


  • Condensers: liquid refrigerant hold-up, proper practices for parallel condenser operation
  • Evaporator defrost best-practices
  • Open question and answer


Todd Jekel

Todd Jekel, PhD, PE is the assistant director of the Industrial Refrigeration Consortium at the University of Wisconsin–Madison. Jekel has been actively conducting research on refrigeration systems including vessel design practices, oil separators, and analysis of dehumidification alternatives for cold storage warehouses. He holds degrees from Calvin College and the University of Wisconsin–Madison.

Upcoming dates (1)

Dec. 1-3, 2021

Madison, WI
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Program Director

Douglas Reindl

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We can deliver this course as an on-site learning experience tailored to your organization’s specific training needs.