Insulation and T-shaped Flooring: Key to Refrigerated Containers
The two core structural elements that truly determine the success or failure of the cold chain are The Container's insulation layer and the T-shaped floor. Many incidents involving cargo spoilage or uneven internal temperatures stem not from refrigeration unit malfunctions, but rather from a lack of understanding regarding the principles of these components and proper loading practices.
The wall, roof, and floor panels of refrigerated Containers feature a composite sandwich structure. The core is filled with high-density foamed insulation material—predominantly polyurethane (PU) or polyisocyanurate (PIR)—while the inner and outer surfaces consist of a corrosion-resistant metal liner and marine-grade external steel plating, respectively.
1Blocking External Heat Ingress: During long-distance ocean voyages characterized by significant day-night temperature fluctuations and exposure to intense heat and sunlight, the insulation minimizes external heat infiltration. This reduces the load on the refrigeration unit, maintains a stable set temperature, and prevents frequent fluctuations that could damage perishable goods or pharmaceuticals.
2Retaining Internal Cold Energy: It minimizes the loss of cold energy to the outside environment, thereby reducing energy consumption and extending the service life of the refrigeration unit.
3Contributing to Structural Strength: The foam layer is tightly bonded to the metal panels, reinforcing the container's compressive strength and enabling it to withstand the stresses of stacking at sea and the impacts associated with loading and unloading operations.
Unlike standard dry containers that feature flat flooring, refrigerated containers utilize a specialized floor structure made of extruded aluminum alloy featuring longitudinal T-shaped ridges. The spaces between these ridges form ventilation channels that run the entire length of the container; this configuration is known as the T-floor.
Cold air discharged by the refrigeration unit's fan is first directed into the channels beneath the floor, traveling the full length of the container from the bottom up through the cargo. After absorbing heat from the cargo, the air flows back to the refrigeration unit via the gaps between the cargo and the container ceiling. This creates a complete, closed-loop airflow cycle, ensuring uniform temperature throughout the container and eliminating localized "hot spots" where temperatures might otherwise rise.
1Bottom Air Supply for Uniform Temperature: Cold air diffuses upward from the base of the cargo, preventing a scenario where the upper layers are cold while the bottom cargo suffers from stifling heat and spoilage; this ensures the stable transport of fresh produce and frozen goods.
2Drainage and moisture wicking: Condensation generated during transport flows along the channels to the drainage outlet, preventing water accumulation, dampness, and mold inside the container.
3Load-bearing capacity: High-strength aluminum alloy profiles meet the load-bearing requirements for pallets and heavy cargo.
The insulation layer blocks external heat, while the T-floor distributes internal cold; both are indispensable.
