What is a Reefer Container？

A reefer container, or refrigerated container, is a temperature-controlled shipping unit that is used to transport perishables. Its main role is to maintain the ideal temperature to keep your product fresh and safe until it reaches the end consumer.

Because of this, its popularity has become widespread across industries that depend on temperature-controlled transport.

Table of Contents

What is a Reefer Container?

To simplify, a reefer container is a shipping container used to keep the ideal temperature required for the cargo (not to cool or freeze products).

Reefer containers are not designed to cool large loads of warm goods to their target temperature. Because of this, cargo must be pre-cooled to its ideal temperature before it is placed inside the container. Once loaded, the reefer’s job is to remove the trapped heat and keep that stable temperature throughout the transit.

The reefer container is equipped with a refrigeration system that makes this possible. Depending on the design, model, and cargo requirements, it can keep temperatures from -30°C to +30°C. Many industries utilize this container to keep their products in the best condition during transport.

How Does a Reefer Container Work?

While it may look like a giant refrigerator, a reefer container uses a special bottom-up airflow system to keep a large amount of cargo at a steady temperature. The cool air flows through the floor and flows upward through the goods to keep the ideal temperature throughout the entire shipment.

Temperature Control System

A reefer container works like a controlled mobile cold environment that helps keep cargo at a specific pre-set temperature during transport. It uses a built-in refrigeration unit that constantly monitors temperature conditions and changes them as needed.

This system helps stabilize the environment for temperature-sensitive products, even when the outside temperature changes during the journey.

Controller Setting

At the front of the unit, you will find the controller where you set the required conditions for the shipment – its temperature, ventilation, and humidity levels. This system manages cooling throughout the journey.

Power Supply

The refrigerated container is powered through an external connection. Power is available at terminals, on vessels, or through a portable generator (also called a genset) when transported by truck or train.

Cargo Space

Inside a standard 40-foot high cube reefer container, you get about 67 cubic meters of cargo space, which is equivalent to roughly 23 Euro pallets or 20 American pallets.

The wide space supports proper airflow between and around the cargo to keep the ideal temperature throughout the entire load.

T-Bar Floor System

The T-bar floor allows cold air to circulate underneath the cargo and then pass upward through the load. This bottom-up airflow distributes temperature evenly across the entire container.

As a result, it helps keep the temperature conditions stable for the cargo throughout the transport.

Air Guide

The air guide, also called the baffle plate, directs airflow from the refrigeration unit so cold air is properly distributed throughout the reefer container. The airflow is guided in the correct direction to improve circulation and provide stable temperature across the cargo.

Structural Design

The floor is fully welded to provide higher strength and to make cleaning easier. At the same time, scuff liners on the side panel protect the interior from damage during loading and unloading to add durability and extend the refrigerated container’s service life.

Drain System

Drain points are located at each corner of the reefer container to allow the trapped moisture to escape. These are kept closed during frozen shipments to keep a stable temperature.

Load Line Limit

A red load line marked on the walls shows you the maximum safe height for cargo loading. If you load above this line, air is blocked to flow inside which reduces cooling efficiency.

Sealing and Protection

After you finish loading, you close and seal the door to prevent outside air from entering the refrigerated container. To seal it, use a seal pin and/or a container security seal to make sure it is tightly secured on the door locking system.

From that point, the reefer container continuously circulates cooled air to maintain the set temperature and keep your cargo in stable conditions. The refrigeration system keeps monitoring internal conditions and stabilizes the level to keep the ideal temperature until it reaches its destination.

How Does a Reefer Container Work for Different Types of Products?

A reefer container can handle anything from deep freeze (around -30C) up to a mild cool (about +30C), depending on what’s being shipped. Now let’s see how that works for different kinds of cargo:

Fruits and Vegetables

Usually kept chilled, not frozen (around +2°C to +13°C)
The reefer removes moisture and CO2 and can use ventilation to slow the ripening process.
Some reefer containers adjust gas levels (controlled atmosphere) to keep produce fresher longer.

Frozen Food

Loaded already frozen, with the reefer set at -18°C to -25°C or colder.
The goal is to keep the product solid the whole trip, with no thawing.
Solid block stowage is used (cargo is tightly stacked with no gaps) to maintain even temperature.
Good airflow between pallets is important to avoid warm spots.
Venting is normally closed to avoid warm air pockets and keep the cold air uniform.

Dairy Products

Usually stored just above freezing levels (+1°C to +7°C)
Keeps dairy products safe without freezing.
Keeping a stable temperature helps avoid spoilage and texture loss.

Pharmaceuticals and Medical Supplies

Many medicines need to be stored at temperatures between +2°C and +8°C, or even -20°C for deep-frozen drugs.
Reefer containers record temperature continuously and often link to tracking systems.
Both cargo and containers are usually pre-cooled, since reefer containers hold temperature better than cool warm loads.

Flowers and Plants

Usually shipped cool but not frozen, around +2°C to +10°C.
Temperature and humidity are controlled to slow aging and keep blooms fresh.
Some reefers have settings to help flowers arrive looking freshly cut.

Chemicals

Some chemicals, adhesives or resins need to avoid high heat or freezing temperatures.
Reefers keep them within the specified interval in the safety data sheet, usually between +10°C to +25°C or refrigerated.
They also help limit sudden changes and condensation, sometimes with special packaging or ventilation.

Remember!

Set the right temperature, arrange the cargo properly so cold air can circulate freely between pallets, and keep the reefer container powered so cargo keeps its quality from start to finish.

Types of Refrigerated Containers

Refrigerated containers come in several types, grouped mostly by size, function, and how they are cooled. Here’s a simple breakdown.

By Size: Reefer Container Dimensions

20RF Reefer Container

The internal volume of a 20RF reefer container is approximately 28.4 m³ (1,003 cu.ft).

The refrigerated container is designed to withstand extreme environments ranging from -40°C (-40°F) to +80°C (176°F), ensuring that the basic structural integrity remains unaffected. The refrigeration unit, installed at the front of the container, offers excellent cooling performance, maintaining a stable internal temperature of -20°C even when the external temperature reaches 38°C.

Quality inspections show that the container’s thermal leakage value (U) is 23 kcal/°C·hr at an average wall temperature of 293K (20°C), and the air leakage value (Q) is 3.0 m³/hr at 250±10Pa, significantly reducing heat and air exchange, ensuring temperature stability within the container, and providing an optimal storage environment for goods.

40RH Reefer Container

The internal volume of a 40RH reefer container is approximately 67.89 m³ (2,398 cu.ft). Compared to the 20RF reefer container, the 40RH offers a more spacious interior, allowing for the transport of a greater quantity of goods and meeting the needs of high-volume shipments.

The refrigerated container is designed to withstand extreme environments ranging from -30°C (-22°F) to +80°C (176°F), ensuring that the basic structural integrity remains unaffected. The refrigeration unit, installed at the front of the container, delivers excellent cooling performance, maintaining a stable internal temperature of -18°C even when the external temperature reaches 38°C.

Quality inspections show that the container’s thermal leakage value (U) is 42 kcal/°C·hr at an average wall temperature of 293K (20°C), and the air leakage value (Q) is 3.0 m³/hr at 250±10Pa, significantly reducing heat and air exchange, ensuring temperature stability within the container, and providing an optimal storage environment for goods.

By Function

Standards Reefer

Basic temperature-controlled container, usually for chilled or frozen goods in a single temperature range (roughly between -30°C to +30°C)

Blast Freezer

Uses a powerful refrigeration unit to pull heat out of already cold products much faster than a standard reefer. This helps the products to reach a stable frozen state quickly before long-haul transport.

Controlled / Modified Atmosphere

CA/ MA Reefer containers adjust oxygen, CO2, and humidity to slow ripening and keep the quality of fruits, vegetables, and some flowers.

Automatic Fresh Air Management (AFAM)

This kind of reefer container automatically regulates the flow of air and exchange of gases to fine-tune cooling and keep produce fresher longer.

By Cooling Design:

Integral (self-powered) Reefer

Has a built-in refrigeration unit and needs only external power (ship, truck, or plug-in). This is the most common modern type.

Porthole Reefer

Container with insulation and vents; cooling comes from an external unit attached through a porthole at the door end. This is often used on older or special setups.

Insulated Non Self-Powered Reefer

Well-insulated box that has no built-in refrigeration unit and relies entirely on an external cooling source like a centralized chiller or refrigeration system connected from the outside.

Because it depends on that external unit, it is mainly used in fixed-site applications like on-site cold rooms, warehouse cold zones, or temporary cold storage where the container stays in one place.

Composition of Reefer Containers

A reefer container is a special type of container equipped with refrigeration equipment, allowing it to regulate the temperature and ensure that temperature-sensitive or perishable goods are well-preserved during transportation. An ISO-standard reefer container mainly consists of the container body structure, insulation materials, and refrigeration system.

Container Body Structure

The container is made of steel components, including insulated side panels with corrugated outer sheets and inner linings, an insulated floor with aluminum “T” profile railings and corrugated flooring, an insulated roof with outer sheets and corrugated inner linings, insulated doors with outer sheets and corrugated inner linings, and ISO corner fittings.

Insulation Materials

Insulation materials prevent heat transfer, thereby reducing the operation time and energy consumption of the refrigeration equipment. Considering that the container needs to withstand the pressure of the cargo and potential external impacts, the insulation material used in reefer containers is primarily rigid polyurethane foam with a density of 40-55 kg/m³ and a thickness of 60-110 mm. This material is distributed across the container’s side panels, floor, roof, and doors.

Refrigeration System

The refrigeration unit is the core component of the refrigeration system in a reefer container. It regulates the temperature inside the container and maintains a stable low-temperature environment to ensure the safety of goods during transportation. Commonly used refrigeration unit brands for reefer containers are Thermo King and Carrier. These units are equipped with intelligent control systems and remote monitoring capabilities, allowing for real-time temperature and system status monitoring, ensuring precise temperature regulation at any time and from anywhere.

Advantages of Using Reefer Container

Using a reefer container provides advantages, especially for temperature-sensitive products.

Keeps Products Safe and Fresh

Reefer containers maintain a steady, controlled temperature, so food, medicine and other goods keep their quality throughout the shipping time.

Minimizes Food Spoilage

By holding the right temperature and often managing humidity, reefer containers reduce spoilage of perishables like fruits, dairy, and frozen foods, which means minimized waste and rejected shipments.

Extend Shelf Life

The stable cold environment inside a refrigerated container slows down ripening, aging, and the growth of bacteria. This helps products arrive with a longer remaining shelf life.

Works Across Many Cargoes and Routes

Refrigerated containers can handle frozen and chilled goods, so they are useful for food, pharmaceuticals, flowers, and chemicals. They move easily by ship, truck, and rail for flexible, global shipping options.

Allows Control through Monitoring

Modern reefer containers have built-in monitoring so you can track conditions and make quick decisions if something goes wrong.

Cost-Effective in the Long Run

Even though reefer containers cost more to run than dry containers, they save money by reducing losses, avoiding emergency air shipments and letting you ship higher-value, perishable goods.

Wrapping Up

A reefer container is a carefully designed, mobile cold room that helps keep food products, medicine, and other sensitive goods safe and fresh while they travel. As long as the cargo is pre-cooled, stacked carefully to let the air flow, and the unit stays powered.

A reefer container makes it possible to ship items across the world without losing quality.