Intermediate Ammonia Refrigeration Systems

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

• 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

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. Course can be taken individually as well.

Attendees participating in this course will be able to earn a digital badge as evidence of the knowledge they obtained during the course. Digital badges are micro-credentials that can be earned by successfully passing a final quiz administered online after completing the course. Click here for information on digital badges.

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

Evaporators

• 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

Troubleshooting

• 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 (IRC) at the University of Wisconsin–Madison, where he leads applied research and technical outreach in industrial refrigeration. His work focuses on system and component modeling, refrigeration load and energy calculations, accumulator design, and safety relief vent systems. Dr. Jekel has contributed to the development and instruction of several web-based and in-person courses for refrigeration professionals, covering topics such as ammonia refrigeration, process safety, and energy efficiency. He holds degrees from Calvin College and the University of Wisconsin–Madison. In addition to his academic and research roles, he is an active member of ASHRAE and the International Institute of Ammonia Refrigeration (IIAR), serving on multiple technical committees. Dr. Jekel is recognized for his expertise in vessel design, oil separation, and dehumidification strategies for cold storage facilities.

Marc Claas

Marc Claas is an Associate Researcher with the Industrial Refrigeration Consortium, specializing in industrial refrigeration since 2009. He focuses on system maintenance, safe operation, troubleshooting, and regulatory compliance, with a growing interest in emerging cooling technologies. Marc has led online operator training programs and brings extensive field experience in Process Safety Management (PSM), including audits and Process Hazard Analyses (PHAs). He also investigates energy efficiency and operational improvements in refrigeration systems. Marc holds a B.S. in Mechanical Engineering from UW-Platteville and an M.S. in Mechanical Engineering with a focus on Thermal Sciences from UW-Madison. He is an active member of the International Institute of Ammonia Refrigeration.

Douglas Reindl

Douglas Reindl, PhD, PE is a professor in the Department of Mechanical Engineering and a Program Director at the Office of Interdisciplinary Professional Programs at the University of Wisconsin–Madison. He brings extensive expertise in mechanical systems, with a particular focus on industrial ammonia refrigeration. As the founding director of the Industrial Refrigeration Consortium, Dr. Reindl is dedicated to advancing the safety, efficiency, and reliability of refrigeration infrastructure. He holds a BS in Mechanical Engineering Technology from the Milwaukee School of Engineering, and both MS and PhD degrees in Mechanical Engineering from UW–Madison. A registered professional engineer in Wisconsin, Dr. Reindl is widely recognized for his leadership in refrigeration education and applied research.