Pre-cooling

• Proper pre-cooling of the products is crucial as it rapidly removes heat from commodities before shipping, storage and processing.
• All refrigerated cargo should be pre-cooled to the recommended carrying or storage temperature before it is loaded into a container.
• Proper product pre-cooling reduces the rate of water loss and spoilage for many perishables, and helps maintain freshness and quality.
• Reefer containers are built to maintain the temperature of the products, and not to decrease their temperature.

Loading of refrigerated cargo in a proper loading facility.

Pre-cooling of reefer container

• Pre-cooling of reefer container is required only when a proper loading bay is available where the temperature in the cold store and in the container are identical. Proper loading facilities as shown below consist of a tight insulated duct between the cold store and container to prevent warm, highly humid ambient air from entering the reefer container.
• Pre-cooling of the reefer container should NOT take place if no proper loading facilities are available due to the following reasons:
• Condensation on the evaporator coil occurs when warm humid air enters the container during stuffing. This results in the formation of ice, which needs frequent defrosting and eventually affects the cooling capacity that is required for the cargo.
• High condensation occurs on the interior surfaces of a reefer container such as the T-floors and sidewalls caused by the same hot humid air entering the container during stuffing. This eventually results in ice build-up for frozen cargo and causes damage on packages for perishable cargo. In some cases, condensation on perishables can even contribute to the spread of diseases.
• The above-mentioned problem often occurs in a tropical climate when open reefer cargo loading takes place in high temperature and high humidity environments.
• For frozen cargo, ice build-up is one of the factors that causes overweight reefers, and in some cases, results in poor air circulation as the ice formed on the T-floor and sidewall restricts airflow, especially in a situation where the container drain plug is clogged.