Transporting a consignment surely needs the containers to be durable and weatherproof, but when it comes to transporting perishable goods, parameters like temperature become non-negotiable. To solve this, we use Reefer containers
Reefer container is suitable for cargo that is temperature sensitive and requires refrigeration during the voyage. Considering it, a reefer container can be thought of like a refrigerator that can be taken across the route without spoiling the contents. It is a type of intermodal freight container of a refrigeration system. While being stationed on a land-based site, reefer containers need an external power supply. During transit, they can be powered by diesel generators. Reefer containers can achieve a temperature range of -65℃ to 40℃. In absence of an adequate heat ventilation system, reefers have a water cooling system that helps for venting heat.
Reefers have changed the course of trade significantly as fresh goods can be shared with anyone in the world at any given time of the year. Reefers keep the perishable articles safe and transport them safely without changing the quality or quantity, to meet the demand.
To conclude, reefer containers:
Refrigerated containers have similar functionality as a Refrigerator. The general working remains the same for all the types of reefer containers and the respective methods of cooling used. Their specific T-shaped decking is designed to distribute cool air from the surface. As a result, they are called bottom air delivery units. This type of container design makes, Reefers have a consistent and uniform supply of air and guarantee a good atmosphere with the perfect exchange of air with the cargo.
Even in harsh conditions, refrigerated containers can conserve or lessen the temperature of the shipment. Reefer’s can also maintain a temperature of up to 30℃ for some specific goods when required. The lowering or maintaining of temperature is achieved from a control box usually found near the cooling mechanism.
Reefer Container Temperature Control for Frozen and Chilled Cargo
In Reefer Containers, it is important to maintain the prescribed temperature. This is achieved by circulating temperature-controlled air internally, throughout the cargo space. The type of packaging used and the method of cargo loading affects airflow. Different types of cargo have different temperature, loading, and packaging requirements. Generally, chilled cargo is kept separate from frozen cargo due to different air circulating needs.
For chilled cargo like meat, the packaging used should have ventilation for air to flow through. To remove heat and gases, the air has to flow through the cargo. The main reason for this type of airflow is that the heat is generated by the cargo, in addition to the heat from the outside atmosphere.
For frozen cargo like fresh fruits and vegetables, the respiration process and airflow requirement are different. They require air to flow through the commodity as well as around it to remove gases like Carbon Dioxide and Ethylene (formed due to the respiration of fruits). To achieve this airflow, the cargo is stacked so that there are no gaps between the packages and the walls of the container. As no heat is produced by the cargo, the reefer container fan only needs to remove the outside heat which penetrates through the container walls.
Atmosphere control and fresh air circulation are also extremely important while transporting fruits and vegetables. Carbon Dioxide and Ethylene gases are released because of continuous respiration from this kind of cargo. Excess presence of these gases can lead to product damage, uncontrolled ripening, bad flavor, and aging. Most reefer containers are equipped with Atmosphere Control and proper ventilation to remove these gases and maintain product quality.
Reefer Containers are usually powered by a generator that is attached to the container and provides electricity to the Cooling Unit. These generators can be either fuel-powered or electric-powered or both. Some reefer containers have a secondary generator set to act as a backup in case the primary fails.
While packing a reefer container, there are a few cargo stowage principles that need to be followed to allow proper airflow and efficient loading.
The price of reefer containers is usually six times that of a general-purpose/ standard container. It also varies based on the cooling mechanism used, size of the container, and additional modifications/ customizations made.
Price of a 40’ Reefer Container is usually between $7,500 (refurbished/ used) to $27,000 (new).
These are the types of Reefer Container available:
This is the most commonly used Reefer Container. It comes with an integral front wall and an all-electric automatic cooling and heating unit.
This type of reefer container uses insulation to maintain a constant atmosphere. This is achieved by replacing the consumed oxygen using an air exchange system. This helps in controlling the atmosphere at equilibrium with the product’s deterioration rate.
These are highly advanced reefer containers that use superior technology to regulate the airflow by automatically adjusting the rate of fresh air supply. They work in a way similar to CA Reefer Containers in controlling the composition of Oxygen, Carbon Dioxide, and other gases. The controls for this reefer can be modified to extend the shelf life of the products.
These containers use the Total Loss Refrigeration method to keep the perishable products fresh. Dry Ice or Liquid Nitrogen is used for these containers for cooling. The cryogenically frozen gas evaporates slowly, cools the container, and is then vented out. The average time period for which these containers can maintain their temperature range between 17 days to 30 days.
When transporting highly valuable, temperature-sensitive, or hazardous cargo, system reliability is of utmost importance. Redundant Refrigeration Reefer Containers are used in such cases. These containers have a primary as well as a secondary or back-up refrigeration unit.
Designed to transport products like pharmaceuticals, milk, and general-purpose liquids. These tanks are cooled by circulating brine or synthetic oil around the external coils.
Common Reefer Containers
High Cube Reefer Containers
Offshore Reefer Containers
There are a few other types of Reefer Containers whose dimensions are based on added customizations. These are:
Power consumption of a reefer container will depend on the nature of articles stored, outside temperature, and the number of times the container is opened and closed. Hence, consumption can not be definite in all cases. However, newer models would always consume less power compared to older or used models.
Generally, a range of -25℃ to +25℃ is achieved. For newer containers, it is possible to achieve -40℃ to +40℃. And for Superfreezers, they can achieve up to -60℃.
The sight of docking the reefer container should be well leveled and firm. The container should at least be placed 1 meter away from any walls so that it can breathe, and in case of any repairs, the technician can get enough space to fix it.
Yes, Reefer Containers can be made airtight when all the floor drains and ventilation in the cooling unit has been closed.
A dry reefer container is a modification of a Dry Container fitted with a cooling/refrigeration unit. These types of containers are used to transport temperature-sensitive products that need a dry atmosphere.
Reefer Containers are white because the color white reflects all wavelengths of light and, thus absorbs the least amount of heat. Resulting in the coolant/refrigerant being used less to cool the container’s air.