Industrial Refrigeration Glossary

HFC refrigerant, chlorine-free and ozone-safe. Used in medium-temperature commercial refrigeration (+0°C to +10°C) and automotive AC. Boiling point -26°C, GWP=1430. Replacement for banned R12.

Blend of three HFC gases (R125 + R143a + R134a) used in commercial and industrial refrigeration and freezing. Operates efficiently at low temperatures (-40°C to 0°C). Boiling point -47°C, GWP=3922 (high). Being phased out in favour of eco-friendly alternatives such as R448A and R449A.

Binary blend of R125 + R143a, similar to R404a but more thermally stable. Used in deep freezing (-50°C) and Cascade systems. Boiling point -47°C, GWP=3985. Performs better under variable heat loads.

Natural refrigerant leading large-scale industries (>500 kW) thanks to its superior efficiency (COP > 4) and zero environmental impact (GWP=0, ODP=0). Boiling point -33°C. Toxic at high concentrations, requiring advanced safety systems with Honeywell sensors.

Highly eco-friendly natural refrigerant (GWP=1), used in Trans-Critical CO2 systems in European supermarkets and increasingly in the Gulf. Operates at very high pressure (90–130 bar) with excellent performance in cold to moderate climates. Boiling point -78°C.

Natural hydrocarbon refrigerant with GWP=3 only — the lowest among practical refrigerants. Used in small to medium hermetic units. Flammable, so its use in large systems is restricted and requires specific safety precautions.

Modern HFO blend and eco-friendly direct drop-in replacement for R404a, compatible with existing piping and compressors with minor adjustments. GWP=1387 — 65% lower than R404a. Used in commercial and industrial refrigeration.

General trade name for the family of refrigerants (CFC, HCFC, HFC) developed by DuPont. The term is now commonly used to refer to any refrigerant. Classic Freon variants (R12, R22) are banned worldwide for destroying the ozone layer.

Unit of thermal energy equal to the heat required to raise one pound of water by one degree Fahrenheit. In refrigeration, BTU/hr measures cooling capacity. Example: a 1-ton AC unit = 12,000 BTU/hr.

Unit of electrical or thermal power. 1 kW = 3,412 BTU/hr. Used in refrigeration to measure compressor capacity and power consumption. A 5 HP compressor consumes ≈3.7 kW and delivers approximately 11–15 kW of cooling capacity.

COP = Cooling Capacity ÷ Power Input. The higher the COP, the more efficient the system. Good Freon systems achieve COP=3–3.5, ammonia systems COP=4–5, and CO2 Cascade systems COP=2–2.5.

EER = BTU/hr ÷ Watts. Similar to COP but expressed in imperial units. EER=10 is excellent, EER=8 is good, EER<6 is poor. Used to rate small refrigeration units and air conditioners.

EER calculated over an entire season accounting for varying temperatures. Provides a more accurate measure of real-world efficiency. SEER=15 is very good; SEER=20+ is excellent.

Traditional unit of cooling capacity. 1 TR = 12,000 BTU/hr = 3.517 kW. Derived from the heat required to melt one ton of ice in 24 hours. Example: a 50 m³ cold room requires approximately 3–5 TR depending on the stored product.

Measures a material's ability to conduct heat, expressed in W/m·K. The lower the K-value, the better the insulation. PUF panel: K=0.022, glass wool: K=0.040, Quadcore (Kingspan): K=0.018 — best in class globally.

U-Value = K ÷ Thickness. Measures how much heat passes through one square metre of panel per 1°C temperature difference. Lower U-values mean better insulation. A 100 mm PUF panel achieves U=0.22 W/m²K.

The heart of any refrigeration system. Compresses the refrigerant gas, raising its pressure and temperature. Types: Semi-Hermetic (Bitzer, Copeland) for industrial use; Hermetic (Tecumseh) for small units; Screw (Bitzer CSH) for large capacities; Scroll (Copeland ZB) for quiet operation.

The indoor unit inside the cold room. Absorbs heat from the air as the refrigerant evaporates within it. Types: Cubic for medium rooms (Friga-Bohn DUAL-O); Ceiling-mounted for low-height rooms; Display for commercial refrigeration cases.

The outdoor unit. Rejects the heat absorbed by the evaporator into the ambient air. Types: Air-Cooled (most common in Saudi Arabia); Water-Cooled for large capacities; Evaporative for superior efficiency.

Reduces the pressure and temperature of the refrigerant before it enters the evaporator. Types: Thermal TXV (conventional mechanical); Electronic EEV by Danfoss (±0.1°C accuracy, 15% energy saving); Capillary tube for small units.

Absorbs moisture and contaminants from the refrigerant to protect the compressor and valves. Contains a Molecular Sieve desiccant. Must be replaced at every major service or system change. Common brands: Danfoss DCL, Castel 4316.

A transparent window on the liquid line for monitoring refrigerant state and moisture content via a colour indicator (green = dry, yellow = high moisture). Essential for diagnostics. Brands: Danfoss SGN, Castel 3740.

Electromechanical valve that opens or closes the refrigerant line on electrical command. Used to stop refrigeration when the set temperature is reached and during defrost cycles. Brands: Danfoss EVR, Castel 1078.

A metal vessel after the condenser that stores liquid refrigerant and releases it on demand. Ensures a stable supply to the expansion valve. Sized at typically 30–50% of the full system charge.

Separates lubricating oil from the refrigerant discharge gas and returns it to the compressor. Essential in large systems (>50 kW) to prevent oil accumulation in the evaporator and degradation of heat-transfer efficiency.

Traditional system in which the refrigerant expands directly inside the evaporator within the cold room. Simple, cost-effective, and the most common choice for small to medium systems. Drawbacks: large refrigerant charge and difficult maintenance on large installations.

Uses a secondary fluid (brine or glycol) to cool the rooms instead of circulating refrigerant directly. Benefits: 80% reduction in refrigerant charge, improved safety, and easier maintenance. Widely used in European supermarkets.

Two-stage system: a high-temperature stage (R134a, R404a) pre-cools a low-temperature stage (CO2, R23) to achieve -70°C to -90°C. Essential for pharmaceutical applications, laboratories, and mRNA vaccine storage.

Centralised refrigeration system combining multiple compressors (3–12) in a single rack unit serving dozens of refrigeration points via shared pipework. Benefits: 40% energy saving, Lead/Lag redundancy, heat recovery, and centralised maintenance.

Cutting-edge system operating CO2 (R744) above its critical point (>74 bar). 100% eco-friendly (GWP=1) with high efficiency in temperate climates. Requires ejector technology in hot climates. Widely regarded as the future of commercial refrigeration.

Dynamically modulates refrigerant flow to match the demand of each evaporator. Highly flexible, supports simultaneous cooling and heating in different zones. Widely used in commercial buildings and offices.

Control algorithm combining Proportional + Integral + Derivative terms to reach the target temperature quickly and stably without oscillation. Used in advanced controllers such as CAREL pCO5 and Danfoss EKE.

Periodic process to melt frost accumulated on the evaporator. Types: Electric (common, 4–6 cycles/day); Hot Gas (fast, used in rack systems); Off-Cycle (for rooms above +2°C only). Cycle duration: 15–30 minutes.

The difference between refrigerant temperature at the evaporator outlet and the evaporation temperature. Must be maintained at 5–10 K to protect the compressor from liquid ingestion. The electronic EEV valve controls superheat dynamically with high precision.

Additional cooling of the liquid refrigerant after the condenser to boost system efficiency. Each additional 1°C of subcooling improves efficiency by 1–2%. Typically 3–7 K, measured via the sight glass and temperature sensors.

Device that continuously records temperature and humidity for monitoring and compliance purposes (HACCP, GMP). Stores years of data and generates reports. Leading brands: Testo, Eliwell TelevisSystem, CAREL boss™.

Instant alerts triggered by: temperature rise, refrigerant leak, power failure, or compressor fault. Can send SMS, Email, and Push notifications, and integrate with full BMS systems.

The world's most widely used insulation panel. Consists of high-density polyurethane foam (40–45 kg/m³) sandwiched between two metal skins. K=0.022 W/m·K. Available in thicknesses from 60 mm (medium-temperature cooling) to 200 mm (deep freezing).

Lower-cost alternative to PUF with reduced efficiency (K=0.038). Used for budget-sensitive or temporary applications. Drawbacks: higher moisture absorption and shorter service life.

Outperforms EPS in moisture resistance (K=0.030). Used primarily for floor insulation beneath freezer rooms to prevent cold transfer to the ground.

A plastic or metallic layer that prevents water vapour from penetrating the insulation, where it would condense and cause degradation. Essential in freezer rooms. Typically polyethylene film 0.2–0.5 mm thick.

Blows a high-velocity air stream across the cold room entrance to create an air barrier, preventing warm air ingress and cold air loss when the door is open. Reduces energy loss by up to 70%.

Total heat that must be removed from the room, expressed in kW or BTU/hr. Calculated from: transmission through walls/ceiling/floor, product heat, lighting and equipment heat, personnel heat, and door-opening infiltration. Accurate calculation is essential for correct compressor sizing.

Time required to pull the room temperature down from ambient to the operating setpoint. Typically 4–12 hours depending on room size. Used when calculating the additional compressor capacity required.

Capacity required to maintain the set temperature under normal steady-state conditions after the initial pull-down. Typically 30–40% lower than pull-down capacity. System design is based on whichever figure is greater.

Heat entering through door openings and air leaks in the insulation. Estimated at 5–15% of the total load. Reduced by air curtains, self-closing doors, and thorough insulation sealing.