The state stipulates which enterprises must be equipped with cold storage.

Cold storage is a warehouse that uses cooling facilities to create suitable humidity and low temperature conditions. Also called cold storage. It is a place where agricultural and livestock products are processed and stored. It can get rid of the influence of climate, prolong the storage period of agricultural and livestock products and adjust the market supply. Usage of cold storage: Cold storage is a building that uses artificial refrigeration to make the fixed space reach the specified temperature to facilitate the storage of goods. Cold storage can be widely used in food factories, dairy factories, pharmaceutical factories, chemical plants, fruit and vegetable warehouses, poultry and eggs warehouses, hotels, supermarkets, hospitals, blood stations, troops, laboratories and so on. 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 and so on. The cold storage in northern China is the primary stage of cold storage. According to legend, Beijing Beihai Ice House was built in the Ming Dynasty and has a history of four or five hundred years. /kloc-in the middle of 0/9th century, the world's first mechanical refrigeration device came out, and the low temperature was successfully controlled by artificial refrigeration equipment. Since then, cold storage buildings have developed rapidly in many countries, and all aspects of agricultural and livestock products from harvesting, processing to commodity sales have been refrigerated. The construction of modern cold storage in China began in the early 20th century. At present, large and medium-sized cities have a considerable number of cold storage, and the capacity is increasing. In addition, due to the development of modified atmosphere storage technology, modified atmosphere cold storage has appeared. The decompression cold storage which can create a low-pressure and high-humidity environment is also being studied and designed. According to the nature of use, it can be divided into three categories: productive cold storage, distribution cold storage and life service cold storage. Productive cold storage is an important part of food processing enterprises, which is generally built in areas with concentrated supply. Fish, meat, poultry, eggs, fruits, vegetables and other perishable foods, after proper treatment, are sent to cold storage for cold processing, and then transported to consumption areas for distribution. It is characterized by a large amount of cold work and the overall discharge of stored items. Distributed cold storage is generally built in big cities or land and water transportation hubs and densely populated industrial and mining areas to store grain for market supply and transportation. It is characterized by large cold storage capacity and small freezing capacity, and is suitable for the storage of various foods. Life service cold storage is used to temporarily store food to meet the needs of life, which is characterized by small storage capacity, short storage period, many varieties and low stacking rate. Warehouse site and architectural design cold storage should be built in places with convenient transportation and reliable water and electricity supply sources. There should be good environmental sanitation conditions around the warehouse site, and try to avoid harmful gases, smoke and dust and pollution sources from industrial and mining enterprises. The cold storage of meat, fish and other processing plants should be arranged on the windward side of the minimum frequency wind direction in summer in urban residential areas, close to the place of origin or convenient distribution of goods. Buildings are generally composed of cold storage buildings, cold auxiliary buildings, transportation facilities, management and living buildings and ice-making rooms in computer rooms. Cold working and cold storage buildings are collectively referred to as "cold rooms", including cooling rooms with a temperature of about 0℃, freezing rooms with a temperature of -23 ~-30℃, cold storage rooms with a temperature of-12 ~-20℃ and ice storage rooms with a temperature of -4 ~- 10℃. The layout of the cold storage should make the process flow reasonable, the route short, non-intersecting, the high and low temperature areas clear, the envelope area minimum, the column network neatly distributed, and consider the convenience of expansion and maintenance. Its plane is generally square, and multi-storey cold storage is mostly dumbbell-shaped or monomer-shaped. Dumbbell type divides the high-temperature warehouse and the low-temperature warehouse into two independent enclosure structures, which are connected by a hall in the middle, and the use effect is good. The high and low temperature warehouses are separated from the ground by insulation walls, and the warehouse doors are connected with the normal temperature hall, and air curtains are arranged on the doors to prevent cold air from overflowing. Materials with low thermal conductivity, such as rice husk, cork, asphalt and expanded perlite blocks, should be laid on the walls, ceilings and floors of cold storage as insulation layers to prevent external heat flow from infiltrating into the warehouse and increase the heat load. In order to prevent outdoor water vapor from penetrating into the insulation layer, it is necessary to lay a layer of material with high permeability resistance, such as linoleum, on the high temperature side of the insulation layer as a gas barrier. The structure requires that the cold storage building is generally carried out at room temperature from the beginning of construction to the installation of equipment, and the structural system is also at room temperature; After the cold storage is put into use, its structural system is in a low temperature environment. The deformation of structural system caused by large temperature difference is much larger than that of ordinary buildings, so it is necessary to calculate the temperature stress to prevent "cold bridge". Anti-freezing measures should be taken at the bottom floor to prevent the foundation uplift from damaging the building. At the same time, materials with strong frost resistance should be selected to enhance the frost resistance and durability of the structure. The load-bearing structure of small cold storage is generally beam-slab structure, and large multi-storey cold storage mostly adopts cast-in-place reinforced concrete beamless floor structure. In recent years, prefabricated flat floor and flat floor frame structure constructed by lifting slab method have been gradually popularized. In addition to strength and stability, the structural design of cold storage enclosure wall should also maintain the continuity of insulation layer and gas insulation layer to meet the thermal requirements of buildings. The roof structure of cold storage will expand or contract due to the change of temperature when exposed to the sun for a long time. Precast members should be used to adjust the deformation between members, so as to reduce the total deformation. In order to prevent the roof expansion from adversely affecting the wall, a sliding contact surface can be designed between the roof structure and the wall. Refrigeration equipment Generally speaking, most cold storage rooms are refrigerated in refrigerators. Using liquid (ammonia or freon) with extremely low gasification temperature as coolant, the heat in the storage room is evaporated and absorbed under low pressure and mechanical control, so as to achieve the purpose of cooling. The most commonly used is the compression refrigerator, which is mainly composed of compressor, condenser and evaporation tube. According to the evaporation tube device, it can be divided into direct cooling and indirect cooling. Direct cooling install evaporation tube in cold storage. When the liquid refrigerant passes through the low-pressure evaporation tube, it directly absorbs the heat in the warehouse and cools down. Indirect cooling means that the air in the warehouse is sucked into the air cooling device by the blower, absorbed by the evaporation tube hovering in the cooling device, and then sent to the warehouse for cooling. The advantages of air cooling mode are rapid cooling, uniform temperature in the warehouse, and harmful gases such as carbon dioxide generated during storage can be taken out of the warehouse. Thermal insulation of cold storage: there is obvious temperature difference between cold storage and the outside world, and thermal insulation materials are needed to prevent heat transfer; At present, the commonly used thermal insulation materials are polyurethane (divided into plate and field spraying), extruded board, ordinary foam board and so on. Among them, the polyurethane sprayed on site has the best effect, low thermal conductivity and high cost performance. I. Characteristics and requirements of cold storage buildings Cold storage is mainly used for food freezing processing and cold storage. It keeps the indoor temperature low by artificial refrigeration. The wall, floor and flat roof of the cold storage are covered with a certain thickness of heat insulation material to reduce the incoming heat from the outside. In order to reduce the absorption of solar radiation energy, the exterior wall surface of cold storage is generally painted white or light color. Therefore, the cold storage building is different from the general industrial and civil buildings and has its own 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 cold consumption of cold storage, but also brings moisture into the warehouse. The condensation of moisture leads to the destruction of building structures, especially thermal insulation structures, so it is necessary to set up moisture-proof thermal insulation layers to make cold storage buildings have good sealing performance and moisture-proof and steam-proof performance. The foundation of cold storage is affected by low temperature, so the water in the soil is easy to freeze. Due to the volume expansion of frozen soil, the ground will crack and the whole building structure will be deformed, which will seriously make the cold storage unusable. Therefore, in addition to the effective insulation layer, the ground of low-temperature cold storage must be treated under the insulation layer to prevent soil freezing. A large number of goods should be stacked on the floor of the cold storage, and all kinds of loading and unloading and transportation machinery and equipment should be able to pass through. There are also refrigeration equipment or pipes on the flat roof. Therefore, its structure should be firm and its bearing capacity should be large. In the low temperature environment, especially in the periodic freeze-thaw cycle, the building structure is easily damaged. Therefore, the building materials of the cold storage and the structure of each part of the cold storage should have sufficient frost resistance. Generally speaking, the cold storage building ensures the building quality with its strict heat insulation, tightness, firmness and frost resistance. Ensure the quality of the building. Second, the classification of cold storage (1) According to the scale of cold storage capacity, the current capacity of cold storage is not uniform, generally divided into large, medium and small. The cold storage capacity of large cold storage is above 10000t; The cold storage capacity of medium-sized cold storage is1000 ~10000t; The refrigerating capacity of small cold storage is below 1000t. (2) According to the design temperature of cold storage, it can be divided into four categories: high temperature, medium temperature, low temperature and ultra-low temperature. ① The design temperature of general high-temperature cold storage is -2℃ to+8℃; (2) The design temperature of medium temperature cold storage is-10℃ to-23℃; ③ Low temperature, generally between-23℃ and 30℃; ④ The temperature of ultra-low quick-freezing warehouse is generally -30℃ to -80℃. (3) According to the warehouse structure, it is divided into 1. Civil cold storage This is a kind of cold storage that has been built a lot at present. It can be built in single layer or multi-layer. The main building is generally a reinforced concrete frame structure or a brick-concrete structure. The enclosure structure of civil cold storage is a heavy structure with great thermal inertia. The day-and-night fluctuation of outdoor temperature and the day-and-night temperature fluctuation caused by solar radiation on the outer surface of the envelope are greatly attenuated in the envelope, so the temperature fluctuation on the inner surface of the envelope is small and the storage temperature is easy to be stable. 2. Combined plate cold storage This kind of cold storage is single-layer, and the storage plate is a light prefabricated heat insulation plate assembly structure with steel frame, and its load-bearing members are mostly thin-walled steel. The inner and outer panels of the library board are made of colored steel plates (the base material is galvanized steel plates), and the core material of the library board is foamed rigid polyurethane or polystyrene foam board. Because all the components except the ground are prefabricated in complete sets in professional factories according to unified standards and assembled on site, the construction progress is fast and the construction period is short. 3. Covered soil cold storage is also called soil hole cold storage. Caves are mostly arch structures, with single holes and continuous arch forms. Generally, it is masonry, with a certain thickness of loess covering as insulation layer. When used as a low-temperature covered cold storage, the foundation of the cave should be in the sand layer or bedrock that is not easy to frost heave. Because it has the advantages of adapting to local conditions, using local materials, simple construction, low cost and durability, it has been greatly developed in northwest China. 4. The cold storage in the cave is generally built in hard and complete rock stratum, and the inner side of the cave is generally lined or sprayed with anchor, and the covering thickness of the rock stratum in the cave is generally not less than 20m. 1. Small cold storage is generally divided into indoor type and outdoor type. 1. Ambient temperature and humidity outside the cold storage: temperature+35℃; The relative humidity is 80%. 2. Set temperature of cold storage: fresh storage:+5 ~-5℃; Cold storage:-5 ~-20℃; Low temperature cold storage: -25℃ 3. Cold storage food temperature: L-class cold storage:+30℃; D and J grade cold storage:+15℃. 4. The effective stacking volume of assembled cold storage is about 69% of the nominal volume. When storing fruits and vegetables, multiply by the correction factor of 0.8. 5. The daily purchase volume is 8 ~ 10% of the effective volume of the cold storage. Second, small cold storage Small cold storage generally uses plastic-sprayed color steel plates as panels, and rigid polyurethane foam or high-density polystyrene as insulation materials. The storage has the characteristics of good rigidity, high strength, good thermal insulation performance and flame retardancy. Small cold storage generally adopts eccentric hook connection or on-site foam fixation of embedded parts in the plate wall, which has good sealing performance, convenient disassembly and transportation, small on-site construction and installation, labor saving, good quality and quick effect. Small cold storage is equipped with advanced refrigeration unit, with reasonable matching between storage capacity and refrigeration equipment, fast refrigeration speed, energy saving, full-automatic operation and safe and reliable operation. Small assembled cold storage is widely used, the temperature range is 5℃-23℃, and the special assembled cold storage can reach below -30℃, which can meet different use requirements and is suitable for various industries and departments. Third, the choice of refrigeration equipment for small cold storage. The core of refrigeration equipment in small cold storage is refrigeration unit. The common model of small refrigeration unit is advanced fluorine machine refrigeration equipment. The refrigeration equipment of fluorine machine mostly adopts new refrigerants such as R22, which has little impact on the environment. Fluorine machine refrigeration equipment is generally small in size, low in noise, safe and reliable, with high degree of automation and wide application, and is suitable for small rural cold storage. The combination of refrigerator and condenser used in small cold storage, usually called refrigeration unit, can be divided into water cooling unit and air cooling unit. Air-cooled unit is the first choice for small cold storage, which has the advantages of simplicity, compactness, easy installation, convenient operation and few ancillary equipment. This kind of refrigeration equipment is also beautiful. The refrigerator of refrigeration unit is the heart of refrigeration equipment. Common compression refrigerators can be divided into open, semi-closed and fully closed. The invention has the advantages of small volume, low noise, low power consumption, high efficiency and energy saving. It is the first choice for small cold storage. An air-cooled refrigeration unit with a fully enclosed compressor can be made into a form similar to a split air conditioner and hung on the wall. At present, the better fully enclosed refrigeration compressor on the market, the quality of refrigeration equipment imported from developed countries or Sino-foreign joint ventures is relatively reliable, but the price is more than 50% higher than that of domestic machinery, which is more suitable for small-scale cold storage in cities and towns. Four. Key points in the design of small-scale cold storage The small-scale assembled cold storage with the cold storage temperature below 0 degrees (-16 degrees) needs to set 10 # channel steel overhead on the ground (under the storage board) to make it naturally ventilated. Small cold storage, the temperature in the cold storage is 5~-25 degrees, cold storage board can directly contact with the ground, but the ground should be flat. If a higher height is required, wooden strips can be placed under the cold storage to enhance ventilation; Channel steel can also be placed under the cold storage to strengthen ventilation. V. Suggestions on the design and installation of small-scale cold storage projects In recent years, the development of cold storage projects has become faster and faster, and everyone's understanding of cold storage has become deeper and deeper, and the selection of building materials and various cold storage equipment has become more and more mature. There are two common construction methods for cold storage engineering, one is assembled cold storage engineering, and the other is civil cold storage engineering. At present, the assembled cold storage mostly chooses polyurethane cold storage: that is, the cold storage plate takes polyurethane rigid foam (PU) as the interlayer, and metal materials such as plastic-coated steel plate as the surface layer, combined with the excellent thermal insulation performance and good mechanical strength of the cold storage plate material. It has the characteristics of long insulation life, simple maintenance, low cost, high strength and light weight, and is one of the best materials to choose insulation board for cold storage. The thickness of cold storage board is generally 150mm and 100 mm, and most civil cold storage projects use PU polyurethane foam as insulation board. Freon refrigeration units are mostly used in the selection of refrigeration equipment in cold storage projects, water cooling units are mostly used in large cold storage, and air cooling units are mostly used in small cold storage; At present, Biesel refrigeration unit imported from Germany and Youle unit imported from France have the advantages of stable operation, low energy consumption and low failure rate, so they are the first choice for cold storage at present. Whether the refrigeration equipment is properly configured in the cold storage project is very important. This is because the refrigeration unit with reasonable matching and reliable performance can not only meet the requirements of cold storage capacity and cold storage technology, but also save energy and have low failure rate. At present, some enterprises and individuals who want to build cold storage blindly pursue low prices, ignoring whether the matching of cold storage equipment is reasonable, which leads to the failure of refrigeration effect after use. The reasonable setting of refrigeration equipment matching the cold storage project may increase the investment in the construction of cold storage, but in the long run it saves a lot of money and energy. The after-sales service of refrigeration equipment is also very important, and the operation and maintenance of refrigeration equipment are equally important as technical services. Before building a cold storage, the vast number of warehouse-building enterprises should investigate in many aspects, listen to the opinions of other enterprises on the configuration of refrigeration equipment in the cold storage, and finally determine the feasible scheme for building a cold storage. Let yourself set up your own cold storage with high starting point and high standard, and strive for the best income for yourself.