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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
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