Refrigeration Systems and Refrigerants: A Comprehensive Guide
1. Refrigerants
1.1 Definition
Refrigerant is a fluid used in heat transfer within a refrigeration system. It absorbs heat at low temperature and pressure.
1.2 Designation of Refrigerants
Refrigerants are identified by their chemical formula, name, or a numerical symbolic name when necessary.
2. Refrigerating Fluids (Secondary Refrigerants)
2.1 Definition
A substance used to extract heat by increasing its sensible heat (e.g., brine).
3. Classification of Locations
3.1 Institutional Locations
These are locations where people are held together and do not have full freedom to leave (e.g., prisons, hospitals).
3.2 Public Locations
These are public meeting places where people gather for public and private activities, and occupants have the freedom to leave at any time.
3.3 Residential Locations
These locations include dormitories and other institutional living spaces.
3.4 Commercial Locations
Locations where buying and selling activities take place.
3.5 Industrial Locations
Locations where transformation processes occur.
3.6 Mixed Locations
When different location classifications exist within the same building.
4. Refrigerant Charge in Compression Equipment
For refrigerant charges exceeding three kilograms, the refrigerant must be introduced into the circuit through the low-pressure side.
4.1 Refrigerant Charge Definition
Refrigerant Charge: The total amount of refrigerant contained in a facility, expressed in kilograms.
5. Refrigeration Equipment Components
5.1 Compressor
Compressor: A specific machine, with or without accessories, that raises the pressure of refrigerant vapor through a mechanical operation.
5.2 Volumetric Compressor
Volumetric Compressor: A compressor where vapor compression is achieved by varying the internal volume of the compression chamber.
5.3 Condenser
Condenser: A heat exchanger designed to convert compressed refrigerant gas into a liquid by transferring heat to a medium other than the circulating refrigerant.
5.4 Rupture Disk
Rupture Disk: A device similar to a safety valve, designed to break at a specific pressure, releasing refrigerant.
5.5 Overpressure Safety Features
Overpressure Safety Features: These include safety valves, rupture disks, and fusible plugs.
5.6 Coil
Coil: A chiller or evaporator tube, with or without external fins, forming one or more circuits without mechanical joints.
5.7 Absorption Refrigeration Unit
Absorption Refrigeration Unit: A unit where the refrigerant gas pressure increase is achieved by the absorber and generator.
5.8 Compression Refrigeration Unit
Compression Refrigeration Unit: A unit where the refrigerant gas pressure increase is achieved by the compressor.
5.9 Hermetic Absorption Refrigeration Unit
Hermetic Absorption Refrigeration Unit: Similar to the above, but without mechanical joints.
5.10 Compact Refrigeration Unit
Compact Refrigeration Unit: A unit where all parts are assembled, wired, and tested off-site and transported to the installation location without further assembly between components.
5.11 Semi-Compact Refrigeration Unit
Semi-Compact Refrigeration Unit: A unit where parts are assembled, wired, and tested off-site and transported in sections. Installation requires connection of sections with block valves, but no further mechanical assembly of parts.
5.12 Limited Charge Refrigeration Unit
Limited Charge Refrigeration Unit: A compression refrigeration unit with a limited refrigerant charge and internal volume. If all refrigerant evaporates, the pressure within the circuit will not exceed the maximum working pressure.
5.13 Refrigerant Fluid
Refrigerant Fluid: A fluid used in heat transfer within a refrigeration system. It absorbs heat at low temperatures and pressure and releases it at higher temperatures and pressure. This process involves changes in the refrigerant’s state.
5.14 Refrigerating Hydraulic Fluid (Brine and Similar)
Refrigerating Hydraulic Fluid: A substance used to extract heat by increasing its sensible heat.
5.15 Evaporator or Cooler
Evaporator or Cooler: A heat exchanger designed to receive heat from a medium other than the refrigerant, causing the refrigerant to vaporize (evaporate) and the other medium to cool.
5.16 Generator
Generator: A device where heat separates vapor dissolved in liquid. The vapor is then sent to the absorber at increased pressure, allowing for subsequent liquefaction in a condenser.
5.17 Absorption Group
Absorption Group: The part of an absorption refrigeration unit that includes the refrigeration machinery from the absorber inlet to the condenser inlet.
5.18 Compression Group
Compression Group: The part of a compression refrigeration unit that includes the refrigeration equipment from the compressor inlet (including its drive) to the condenser inlet, along with accessories. If all components are factory-mounted on the same structure, it’s called a compressor unit.
5.19 Condensation Group
Condensation Group: The part of the refrigeration equipment that includes the refrigeration machinery from the compressor inlet (including its drive) or the absorber to the liquid receiver outlet, along with accessories. If all components are factory-mounted on the same structure, it’s called a condensing unit.
5.20 Refrigeration System
Refrigeration System: A combination of refrigeration system elements and specific supplements to achieve heat exchange and control its operation.
5.21 Pressure Limiting Device
Pressure Limiting Device: A device installed in the refrigeration circuit to automatically switch off the compressor or generator when the refrigerant pressure reaches a certain adjustable value.
5.22 Refrigeration Equipment
Refrigeration Equipment: Any of the key elements that make up a refrigeration unit.
5.23 Refrigeration Plant
Refrigeration Plant: Any facility that uses thermal cooling machines as part of a production or packaging process. This includes cold storage facilities, ice plants, central air conditioning systems, and freezing or cooling plants for various products.
5.24 Absorbed Power
Absorbed Power: For hermetic or semi-hermetic compressors, it refers to the maximum electrical power consumed by the motor under the suction and discharge conditions specified by the manufacturer. For open compressors, it’s the nominal power of the electric motor.
5.25 Pressure Test
Pressure Test: The pressure value to which a component or section of a refrigeration unit must be subjected, using the same refrigerant, to check for leaks.
5.26 Working Pressure
Working Pressure: The maximum effective pressure at the operating temperature.
5.27 Liquid Receiver
Liquid Receiver: A container permanently connected to a refrigeration unit with inlet and outlet pipes, used for regulating and storing compressed liquid refrigerant.
5.28 Machine Room
Machine Room: A room where refrigeration equipment is permanently installed. Adjacent rooms connected to the machine room are considered part of it.
5.29 High-Pressure Area
High-Pressure Area: The part of the cooling system under the same pressure as the condenser.
5.30 Medium-Pressure Area
Medium-Pressure Area: In multi-stage systems, the part of the cooling system between the discharge of one stage and the suction of the next (e.g., intercoolers). Its primary purpose is to cool the discharged vapor.
5.31 Low-Pressure Area
Low-Pressure Area: The part of the cooling system under the same pressure as the evaporator.
5.32 Refrigeration Circuit
Refrigeration Circuit: A set of elements forming a closed cooling circuit through which a refrigerant circulates or resides to remove or dissipate heat.
5.33 Fusible Plug
Fusible Plug: A device with an element that melts at a specific temperature, allowing refrigerant to escape and preventing dangerous pressure buildup.
5.34 Mechanical Joints
Mechanical Joints: Discontinuous, rigid, and leakproof connections in refrigerant lines or components, using a mechanical device to hold the surfaces together.
5.35 Soft Welds (Brazing)
Soft Welds (Brazing): Continuous, rigid, and leakproof connections of metal elements, achieved by injecting molten metal alloys with a melting temperature below 550°C and above 200°C.
5.36 Strong Welds (Welding)
Strong Welds (Welding): Continuous, rigid, and leakproof connections of metal elements, achieved by injecting molten metal alloys with a melting temperature above 550°C and below the melting temperature of the joined parts.
5.37 Electric Welding
Electric Welding: Continuous, rigid, and leakproof connections of metal elements, achieved by bringing the parts to a plastic state before merging them.
5.38 Expansion Valve
Expansion Valve: A device that regulates the flow of liquid refrigerant from a high-pressure state to a lower one.
5.39 Section Valve
Section Valve: A device to open, stop, or regulate the passage of refrigerant. Unless otherwise specified, it is manually operated.
5.40 Safety Valve
Safety Valve: A device inserted in the cooling system with an orifice held closed by a spring or similar mechanism. When the refrigerant pressure exceeds a set value, the orifice automatically opens to release pressure.
6. Refrigerant Nomenclature
6.1 Refrigerant Name
6.2 Refrigerant Designation – Numerical Symbol
7. Refrigerant Safety Classification
8. Classification of Cooling Systems
8.1 Direct System
8.2 Closed Indirect System
8.3 Open Indirect System
8.4 Double Indirect Closed System
8.5 Double Indirect Open System
8.6 Closed Indirect Ventilation System
8.7 Open Indirect Ventilation System
9. Project Documentation
The project will include documentation, plans, budget, and specifications. The report will include a summary of features.
10. Fire Suppression Systems
Extinguishing agents used in fire suppression systems must not freeze at the operating temperature of the facility. They must be compatible with the refrigerants used and suitable for electrical and oil fires (if oil-immersed switches are used).
Extinguishing systems must be inspected regularly and maintained in proper working order.