| Medium-Temperature Storage | Dairy products, beverages, fresh produce, packaged food, and general chilled storage.
Typical room temperature: 0 to 10°C. | R134a, R448A, R449A, R290, or R744, subject to local regulations and system design.
R134a has a relatively high GWP of approximately 1,430. R448A and R449A have a lower GWP of approximately 1,400. R290 has a very low GWP of approximately 3.3 but is flammable. | Reciprocating compressors for small and medium capacities.
Scroll compressors for compact systems with stable loads.
Semi-hermetic reciprocating compressors for serviceable commercial installations. | Select a condensing unit according to the required evaporating temperature, not only the room temperature. A common design range is approximately -10 to -5°C evaporating temperature, depending on product load, air temperature difference, and humidity requirements. |
| Low-Temperature Storage | Frozen food, ice cream, frozen meat, seafood, and long-term frozen storage.
Typical room temperature: -25 to -18°C. | R448A, R449A, R452A, R290, or R744, depending on safety requirements, equipment compatibility, and regulations.
R404A is technically usable in some existing systems but has a very high GWP of approximately 3,922 and is increasingly restricted or replaced. | Semi-hermetic reciprocating compressors are widely used for low-temperature duties.
Scroll compressors may be suitable for smaller systems when the compressor has an approved low-temperature operating envelope.
Two-stage or compound arrangements may be needed for very low suction temperatures. | Confirm the compressor's approved evaporating range, discharge-temperature limit, oil return, and motor cooling method. A typical evaporating range is approximately -35 to -25°C, but the exact value depends on the product and refrigeration load. |
| Blast Freezing | Rapid freezing of food products where high refrigeration capacity and short pull-down time are required.
Product temperatures may need to reach approximately -18°C or below. | R744, R290, R448A, R449A, or other approved low-temperature refrigerants.
R744 can provide high volumetric capacity but requires high-pressure components and careful system design. R290 offers low GWP but requires flammable-refrigerant safety controls. | Multiple reciprocating compressors, compound systems, or screw compressors for larger capacities.
Parallel compressor systems can improve capacity control and part-load efficiency. | Prioritize pull-down capacity, discharge-temperature control, oil management, and reliable defrost operation. Size the unit using product load, incoming product temperature, freezing time, air movement, and heat leakage. |
| Small Plug-In or Compact Unit | Small cold rooms, display cases, laboratory refrigerators, vending equipment, and compact commercial freezers. | R290 or R600a may be appropriate where permitted and where the equipment is specifically designed for flammable refrigerants.
R134a may still be found in existing equipment, but its relatively high GWP should be considered. | Hermetic reciprocating compressors are common for compact systems.
Small hermetic scroll compressors may be used where the required capacity and operating envelope are suitable. | Check the maximum refrigerant charge, enclosure ventilation, electrical protection, service requirements, and compliance with applicable flammable-refrigerant standards. Do not convert a system to a flammable refrigerant without an approved redesign. |
| Medium Commercial Capacity | Supermarkets, distribution cold rooms, food-processing rooms, and multiple evaporator installations. | R448A, R449A, R744, R290, or other refrigerants approved for the intended application.
R448A and R449A are commonly considered alternatives in systems previously using R404A, but oil type, expansion-device settings, capacity, and discharge temperature must be checked. | Semi-hermetic reciprocating compressors for flexible service and broad operating ranges.
Scroll compressors for efficient, compact, and relatively low-vibration installations.
Parallel compressor racks for variable load conditions. | Compare rated capacity at the actual evaporating and condensing temperatures. Check seasonal efficiency, part-load performance, sound level, vibration, oil return, crankcase heating, and available service support. |
| Large Industrial Capacity | Large cold stores, food-processing plants, logistics centers, and systems with long operating hours and high thermal loads. | R744, ammonia R717, or approved HFO/HFC-blend alternatives, depending on plant design, location, safety requirements, and operator expertise.
R717 has zero GWP but is toxic and mildly flammable. R744 has a GWP of 1 but operates at high pressure. | Screw compressors for high-capacity, continuous-duty applications.
Large semi-hermetic reciprocating compressors for staged capacity control.
Two-stage or cascade systems for low-temperature applications. | Evaluate total lifecycle cost rather than purchase price alone. Include energy consumption, water or air-cooled condenser requirements, maintenance skill, safety equipment, spare parts, controls, and plant-room ventilation. |
| Natural Refrigerant Priority | New installations designed to reduce direct greenhouse-gas emissions and meet future refrigerant restrictions. | R290: GWP approximately 3.3; flammable.
R600a: GWP approximately 3; mainly used in small, low-capacity systems.
R744: GWP 1; high operating pressure.
R717: GWP 0; toxic and mildly flammable. | Use the compressor type specifically approved for the selected refrigerant. Compressor design, motor cooling, lubricant, pressure rating, and electrical protection are refrigerant-specific. | Low GWP alone does not determine suitability. Confirm flammability or toxicity classification, refrigerant charge limits, pressure ratings, leak detection, ventilation, ignition-source control, technician qualifications, and local code compliance. |
| Compressor Technology Comparison | Use this comparison when the refrigerant and required capacity have already been identified. | All refrigerants must be matched with a compressor approved for that refrigerant, pressure level, oil, and temperature range. | Reciprocating: broad capacity range, serviceable, suitable for many medium and low-temperature systems.
Scroll: compact, efficient, and low vibration; best when the operating envelope is not exceeded.
Screw: suitable for large, continuous-duty systems; higher initial cost and more complex oil management.
Hermetic: compact and sealed; replacement is often preferred to field repair.
Semi-hermetic: serviceable and practical for commercial and industrial applications. | Select based on cooling capacity, operating temperatures, duty cycle, capacity-control needs, sound level, efficiency, maintainability, and total ownership cost. A compressor with a higher nominal rating is not automatically suitable if its evaporating or condensing limits are exceeded. |
| Condenser and Ambient Conditions | Indoor or outdoor condensing units operating in different climates and ambient temperatures. | The refrigerant must remain within its allowable pressure and temperature limits at the design ambient condition. R744 requires particular attention to high-side pressure control. | Air-cooled units are common for simple installation. Water-cooled or evaporative condensers may reduce condensing temperature where water quality and maintenance are acceptable. | Size the condenser for the design outdoor temperature, fouling allowance, fan control, and required condensing temperature. High ambient conditions reduce capacity and increase compressor power consumption. |
| Oil and System Compatibility | Any replacement, retrofit, or new condensing-unit installation. | Refrigerant choice affects lubricant selection, oil return, elastomer compatibility, expansion-device settings, and pressure controls. | Verify the specified oil type and viscosity, crankcase heater requirements, discharge-temperature protection, and minimum suction-superheat requirements. | Confirm compatibility among the compressor, oil, refrigerant, filter-drier, expansion valve, pressure controls, piping, and seals. A refrigerant retrofit should follow the compressor and component manufacturer's approved procedure. |
| Final Sizing Checklist | All cold storage condensing-unit projects. | Choose the lowest-impact refrigerant that satisfies safety, pressure, temperature, capacity, availability, and legal requirements. | Select a compressor whose certified performance data covers the actual evaporating temperature, condensing temperature, refrigerant, superheat, subcooling, and voltage. | Confirm: room and product load; pull-down time; evaporating temperature; design ambient; condensing temperature; refrigerant charge; compressor capacity; motor voltage; defrost method; pipe length and elevation; oil return; noise limits; controls; maintenance access; and local regulations. |
