Refrigerated shipping containers are generally manufactured following international standards and generally need to be certified by international mainstream classification societies, such as GL, CCS, ABS, BV, etc.,
1.About the production of refrigerated shipping container
The refrigerated shipping container main body comprises metal materials, such as Aluminum, MGSS, Corten A, Stainless Steel. The wall surface coating is temperature-resistant, moisture corrosion-resistant and wear-resistant.
Most refrigerated shipping containers use open or semi-closed refrigeration units (built-in type), refrigerated through the refrigeration liquid cycle.
The refrigeration unit’s core functions are compressors, refrigerants, condensers, evaporators, heat exchangers, etc. They are powered by ship power supply, terminal power supply or vehicle power supply (three-phase AC voltage, usually 460V, 440V, 380V, 220V) to maintain the low temperature in the refrigerated shipping container by eliminating the heat flux that penetrates the box due to the temperature difference between the inside and outside of the box.
The refrigeration fluid of the refrigerator is generally Freon products, namely hydrofluorocarbons (i.e. HFC), mainly including R134a, R125, R32, R407C, R410A, R152 and so on.
The wall panels of the refrigerated shipping container are made by splicing insulated box panels through craftsmanship. The heat-insulating box board is made of two pieces of metal sheets covered with adhesive. A polyurethane foam layer is injected into the interlayer at high pressure to achieve the heat-insulating effect.
The refrigerated shipping containers are constructed of sufficient insulation materials. They can maintain a low-temperature requirement for a certain period (usually about 6 hours) in a power outage state. The broad temperature range is -30°C ~20℃.
2.Regarding the power of refrigerated shipping container refrigeration unit
Refrigerated shipping containers have different refrigeration units with various specifications and powers.
Usually, the power of a 20-foot refrigerated shipping container is about 7KW, and the power of a 40-foot refrigerated shipping container is about 12KW;
3.Regarding the temperature requirements for the transportation of refrigerated transport goods
The refrigerated shipping container carries a wide variety of goods with different requirements.
- For refrigerated goods, such as food, fruits and vegetables, flowers, aquatic products, and electronic devices, the general temperature requirement is 2-8℃;
- For cold and fresh goods, such as fresh meat, fish, medicines, etc., the requirement is between 0°C and -5°C;
- Frozen goods, such as quick-frozen seafood, frozen meat, etc. generally require below -18°C;
- Deep-frozen cargo, such as high-risk products and high-grade yeast, may require a temperature between -20°C and -45°C, and freight such as the new crown vaccine may require a temperature below -70°C.
4.About the pre-cooling link of refrigerated transportation
4.1 refrigerated shipping container pre-cooling
Before a refrigerated shipping container is loaded, it usually needs to be pre-cooled. Therefore, pre-adjusting the internal temperature of the refrigerated shipping container to the temperature required for the pre-loaded cargo is a crucial step to protect the shipment.
When transporting refrigerated goods over long distances, the difference between the set temperature and the set temperature in the box cannot exceed 3°C. If transporting refrigerated goods, the temperature error should not exceed 0.25-0.5°C.
Before each refrigerated shipping container is delivered for use, a refrigerated shipping container pre-inspection test is required. The test requires a comprehensive inspection of the box, the refrigeration system, etc., to ensure that the refrigerated shipping container is in good condition and clean. The refrigeration system is in the best condition. The cold box that has passed the inspection should be affixed with an inspection label or certificate.
4.2 Pre-cooling of refrigerated transport cargo
In addition to refrigerated shipping container pre-cooling, goods also need to be pre-cooled.
The refrigerated shipping container is designed to keep the low cargo temperature. Suppose the temperature of the cargo is too high. In that case, the refrigeration system of the refrigerated shipping container will be overloaded, and it may even cause malfunctions and affect the safety of the shipment. If there is no good pre-cooled cargo in the container, due to the large heat capacity of the cargo, the cooling speed will be significantly slowed when directly loaded into the container. Sometimes it takes 15-16h to reach the set temperature requirement.
It should be noted that the pre-cooled cargo and refrigerated shipping container must be sealed and docked in the cold air channel for loading. Suppose the cabinet is installed in an outdoor environment. In that case, hot air entering the refrigerated shipping container will cause moisture condensation to damage the outer packaging and labels of the goods, and the condensation on the surface of the evaporator will affect the cooling effect.