Introduction to Cold Storage Knowledge and Selection Methods

With the rapid development of our country's economy, refrigeration equipment has entered various fields such as supermarkets, commerce, agriculture, and industry, closely linked to our lives. Due to the rapid development of refrigeration, users often do not know how to choose from the numerous manufacturers and diverse varieties in the market, especially when there is a high demand and investment, which increases the difficulty of selection. Here, our Lianyungang freight forwarding company introduces some common knowledge and selection methods for cold storage, which may be helpful for you to choose a cold storage.

The purpose and classification of cold storage

Cold storage is a building that uses artificial refrigeration to bring the temperature in a fixed space to a specified level for storing items. Cold storage can be widely used in food factories, dairy factories, pharmaceutical factories, chemical factories, fruit and vegetable warehouses, poultry and egg warehouses, hotels, restaurants, supermarkets, hospitals, blood stations, military units, laboratories, etc. Cold storage is mainly used for constant temperature storage of food, dairy products, meat, aquatic products, poultry, fruits and vegetables, cold drinks, flowers, green plants, tea, medicines, chemical raw materials, electronic instruments, etc. Cold storage can be classified into different types based on various characteristics.

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The first method is to classify according to the capacity and scale of the cold storage. At present, there is no unified division of cold storage capacity, generally divided into large, medium, and small. The refrigeration capacity of large cold storage is over 10000 tons; The refrigeration capacity of medium-sized cold storage is between 1000 and 10000 tons; The refrigeration capacity of a small cold storage is below 1000 tons.

The second method is to classify according to the refrigeration design temperature. It can be divided into four categories of cold storage: high temperature, medium temperature, low temperature, and ultra-low temperature.

The refrigeration design temperature for general high-temperature cold storage is -2 ℃~+8 ℃; The refrigeration design temperature for medium temperature cold storage is between -10 ℃ and -23 ℃; The temperature of low-temperature cold storage is generally between -23 ℃ and -30 ℃; The temperature of ultra-low temperature quick freezing cold storage is generally -30 ℃~-80 ℃.

The third method is to classify according to the category of library structure.

Firstly, there is the construction of a cold storage facility. This is currently one of the most commonly built cold storage facilities, which can be built as a single or multiple story structure. The main body of a building is generally a reinforced concrete frame structure or a brick concrete structure. The enclosure structure of a civil cold storage belongs to a heavy structure with high thermal inertia. The diurnal fluctuations of outdoor air temperature and the diurnal temperature fluctuations caused by solar radiation on the outer surface of the enclosure structure attenuate greatly in the enclosure structure. Therefore, the temperature fluctuations on the inner surface of the enclosure structure are relatively small, and the storage temperature is easy to stabilize.

Next is the combination plate cold storage. This type of cold storage is in a single-layer form, with steel frame lightweight prefabricated insulation panel assembly structure for the storage panels, and its load-bearing components are mostly made of thin-walled steel. The inner and outer panels of the warehouse board are color steel plates, and the core material of the warehouse board is foamed rigid polyurethane or polystyrene foam board. Due to the fact that all components, except for the ground, are prefabricated in a professional factory according to a unified standard and assembled on site, the construction progress is fast and the construction period is short.

Once again, it's the earth cold storage. It is also known as the earth kiln cave cold storage, and the cave structure is mostly arched, with single cave and continuous arch forms. Generally, it is made of brick and stone masonry, and covered with a certain thickness of loess as an insulation layer. As a low-temperature covered soil cold storage, the foundation of the tunnel should be located on a sand layer or bedrock that is not prone to frost heave. Due to its advantages of adapting to local conditions, using local materials, simple construction, low cost, and durability, it has achieved significant development in the northwest region of China.

Another thing is the cave cold storage. Generally, it is built in rock layers with relatively hard stones and good overall integrity. The inner side of the tunnel is usually lined or sprayed with anchor treatment, and the thickness of the rock layer covering the tunnel is generally not less than 20 meters. Characteristics and requirements

In order to maintain a certain low temperature inside the cold storage, the walls, floors, and ceiling of the cold storage are covered with a certain thickness of insulation material to reduce the heat input from the outside. In order to reduce the absorption of solar radiation, the exterior walls of cold storage are generally painted white or light colored. Therefore, cold storage buildings are different from general industrial and civil buildings in that they have their unique structure.

Cold storage buildings should prevent the diffusion of water vapor and the infiltration of air. When outdoor air invades, it not only increases the cooling capacity of the cold storage, but also brings moisture into the warehouse. The condensation of moisture causes the building structure, especially the insulation structure, to be affected by moisture and freeze. Therefore, a moisture-proof insulation layer should be installed to ensure that the cold storage building has good sealing and moisture-proof insulation performance.

The foundation of a cold storage is affected by low temperatures, and the moisture in the soil is easily frozen. Due to the expansion of soil volume after freezing, it can cause ground rupture and deformation of the entire building structure, and in severe cases, it can render the cold storage unusable. For this reason, in addition to having an effective insulation layer, the low-temperature cold storage floor must also be treated under the insulation layer to prevent soil freezing.

The bottom plate of the cold storage needs to stack a large amount of goods and pass through various loading and unloading transportation machinery and equipment, so its structure should be sturdy and have a large bearing capacity. In low-temperature environments, especially during periodic freezing and melting cycles, building structures are susceptible to damage. Therefore, the building materials and various components of the cold storage must have sufficient frost resistance.

Overall, cold storage buildings ensure the quality of the building through their strict insulation, sealing, durability, and frost resistance.

Choose a suitable cold storage facility

Lianyungang import freight forwarders determine the size of the cold storage based on the tonnage of their stored goods, daily purchase and shipment volume, and the size of the building, as well as the specifications and opening direction of the warehouse doors. The installation environment of the cold storage should be clean, dry, and well ventilated.

Select and determine the temperature inside the warehouse based on the stored items. Choose preservation storage (+5 ℃~-5 ℃), refrigeration and freezing (0 ℃~-18 ℃), or low-temperature storage (-18 ℃~-30 ℃).

According to the characteristics of one's own building and the local water source situation, choose the cooling method of the refrigeration machine, generally including air cooling and water cooling. The refrigeration machine is air-cooled, and users only need to choose the placement location; For water-cooled refrigeration systems, users also need to configure the size of the water tank, deep water wells, circulating water pipelines, inlet and outlet pipelines, as well as the placement of water pumps and cooling towers.

Complete the construction of auxiliary facilities

Install a 10cm stone filling layer on the foundation of the cold storage, and then pour 5-10cm concrete. The ground must be level. Expansion joints or ventilation ducts should be reserved on the ground of the low-temperature warehouse to prevent the foundation of the cold storage from being affected by low temperatures, which may cause the ground to crack and the entire cold storage structure to deform due to volume expansion after freezing.

According to the load capacity of vehicles entering and exiting (except for people entering and exiting), the floor of the cold storage should not only be waterproof and insulated, but also reinforced. Steel mesh should be laid with Φ 10-14mm threaded steel, and concrete with a thickness of 10-25cm should be poured.

Users who choose water-cooled refrigeration machines should drill deep water wells or build a water pool near the cold storage according to the factory's requirements, and lay circulating water pipes to connect to the cooling tower and unit locations.

Configure a power supply (three-phase four wire) that meets the requirements of the cold storage, connect the power supply to the side of the cold storage, and install a dedicated safety switch.