Technical Information > Temperature Performance of Reefer Shipping Containers

Temperature Performance of Reefer Shipping Containers

What Does Temperature Performance Mean for a Refrigerated Shipping Container?

The temperature performance of a refrigerated shipping container (also known as a “reefer” container) represents the complex capability of the equipment to maintain, regulate, and document precise temperature, humidity, and atmospheric conditions inside the cargo space regardless of the external environment. It is not merely the ability to cool, but a dynamic interplay of sophisticated technology, highly efficient insulation, intelligent control, and proper cargo handling. This property is crucial for the transport and storage of perishable goods, pharmaceuticals, flowers, and sensitive chemicals.

Principle of Operation and Key Components of a Refrigerated Container

ComponentDescriptionTechnical Parameters and Trends
Cooling UnitThe main technological unit ensuring cooling, heating, dehumidification, and ventilation. It consists of a compressor, condenser, expansion valve, and evaporator.Modern units (e.g., MicroLink 3, Thermo King Magnum Plus) offer efficient operation, low consumption, environmentally friendly refrigerants, and remote monitoring capability.
InsulationSandwich panels with polyurethane foam, between the outer shell (Corten steel) and inner shell (stainless steel).Polyurethane foam with high thermal resistance. Innovation: vacuum insulation panels (VIP) for even higher efficiency at the same wall thickness.
Air Circulation SystemEfficient air distribution via T-profile flooring, circulation according to cargo type (through or around goods).Air flow optimization minimizes temperature fluctuations, prevents dead zones. Proper cargo handling (spacing, blocking) is important.
Control SystemMicroprocessor control with data logger, sensors for temperature, humidity, CO₂, ethylene.Systems enable remote monitoring, alarm settings, data download (e.g., SmartArctic by TITAN Containers), precise regulation, and data export to Excel.

Details of Key Components

Cooling Unit: The Heart of the System

  • The cooling unit is typically powered by three-phase current (380–440 V), ensuring operation at ports or on the road with the help of auxiliary generators (genset).
  • It operates on the principle of a compressor cycle. Powerful compressors enable reaching extreme temperatures down to -60 °C (Super freezer), standard -25 °C to +25 °C.
  • Modern technology (e.g., MicroLink 3) ensures high efficiency and reduces electrical energy consumption by tens of percent compared to older models.

Insulation: Key to Maintaining Performance

  • Insulation is primarily composed of polyurethane foam with high R-value (thermal resistance), which is injected under pressure; typical insulation thickness is 75–100 mm.
  • Vacuum insulation panels (VIP) enable achieving the same or better insulation performance at lower thickness, which maximizes the usable volume of the container.

Air Circulation System

  • Cold air is forced under T-profiles, rises through or around the cargo, and returns to the cooling unit.
  • For chilled goods (fruit, vegetables), air flow through the cargo is necessary; for frozen goods, air flow around the cargo block.

Control Systems and Monitoring

  • Modern containers are equipped with a microprocessor, data loggers, temperature and humidity sensors, and remote access capability (for example, the SmartArctic system allows monitoring, controlling, and downloading data from anywhere).
  • Alarms can be set for temperature fluctuations, defrosting can be initiated, temperature history can be downloaded, data can be exported to Excel, etc.

Factors Affecting Temperature Performance

External and Internal Influences

FactorDescription and Impact on Performance
Ambient TemperatureThe greater the difference between the required and ambient temperature, the higher the consumption and system load.
Type of CargoLive cargo (fruit, vegetables) produces heat, CO₂, and ethylene; frozen goods are inert.
Loading MethodImproper loading can prevent air flow, creating temperature fluctuations and “hot” or “cold” spots.
InsulationQuality insulation significantly reduces heat gain into the container.
Frequency of Door OpeningFrequent door opening increases heat and moisture intake; the system must cool more frequently and intensively.
Condition of EquipmentPoor maintenance (dirty heat exchangers, insufficient refrigerant, leaks) significantly reduces performance and increases consumption.
Initial TemperatureCargo must be pre-cooled. Cooling warm goods in the container is energy-intensive and risky.

Temperature Ranges and Energy Consumption

Container TypeTemperature RangeTypical UseCooling Power (kW)Consumption (kWh/day)
Standard Reefer-25 °C to +25 °CFood, pharmaceuticals, flowers5–6 (at -18 °C)20–40 (average)
Super Freezerup to -60 °CFish, meat, special goodsup to 8–1060–100 (extreme)
  • Energy consumption increases with decreasing temperature and increasing temperature difference against the environment.
  • Modern technology (e.g., inverter compressors) can reduce consumption by 20–30%.

Measurement and Quantification of Temperature Performance

Key Technical Indicators

  • Cooling Capacity (kW): Indicates the amount of thermal energy the equipment is capable of removing per hour. For a 40′ reefer, a typical value is 5–6 kW at -18 °C.
  • Temperature Stability: The ability to maintain constant temperature throughout the container volume. Modern systems handle fluctuations on the order of tenths of °C.
  • Energy Consumption (kWh): Depending on operating conditions, 2–4 kWh in mild conditions, 9–12 kWh (or more) in extreme conditions or during cooling down.

Recording and Monitoring

  • All modern containers record temperature, humidity, alarm, and system intervention history (data logger).
  • SmartArctic systems enable data export and real-time remote monitoring.

Optimization of Operation and Maintenance

Recommended Practices for Maximum Performance

  1. Pre-cooling of Cargo
    • Always load goods at the required temperature; do not use the container for primary cooling!
  2. Regular Maintenance
    • Cleaning of condenser and evaporator, checking door seals, sensor calibration, sufficient refrigerant.
  3. Proper Loading
    • Maintain gaps under the ceiling (min. 10 cm), do not block air return, breathable packaging for fruit/vegetables.
  4. Use of Modern Technologies
    • Invest in equipment with low consumption, environmentally friendly refrigerant, with remote monitoring and alarm capability.

Trends and Innovations in Temperature Performance

  • Remote Monitoring (SmartArctic, MicroLink, etc.):
    • Ability to control, set, monitor, and download data from anywhere in the world.
  • Environmentally Friendly Refrigerants:
    • Transition to refrigerants with low GWP (Global Warming Potential), e.g., R-452A, R-513A.
  • Better Insulation:
    • Vacuum panels and improved polyurethane foams increase efficiency and reduce costs.
  • Automation and AI:
    • Intelligent systems predict failures, optimize consumption, and provide timely alerts for service interventions.

Related Terms

TermMeaning
Reefer ContainerSynonym for refrigerated/chilled shipping container
Cooling UnitAggregate at the front of the container ensuring cooling, heating, dehumidification, and ventilation
Heat TransferProcess that the system tries to prevent through insulation and cooling
Ambient TemperatureTemperature of the external environment, crucial for system load
Polyurethane FoamMain insulation material of refrigerated containers
Return Air TemperatureKey value for performance control and stability maintenance

Summary

The temperature performance of a refrigerated shipping container is the result of a synergistic combination of advanced cooling technology, highly efficient insulation, smart regulation, and proper cargo handling. Modern containers enable precise setting, control, and remote monitoring, which is essential for safe and efficient transport of sensitive goods across continents. Quality temperature performance means not only maintaining the quality and safety of goods, but also reducing costs and environmental impact.