First, the cold storage is mainly used for food freezing processing and refrigeration. 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 piled up 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 freezer panel and all parts of the cold storage should have sufficient frost resistance.
Generally speaking, refrigeration equipment ensures the quality of buildings with its strict heat insulation, tightness, firmness and frost resistance. Ensure the quality of the building.
Second, 1. Civil refrigeration equipment
This is a kind of cold storage that is built more at present, which 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 equipment is in single-layer form, and the warehouse board is a light prefabricated heat insulation board 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 cold storage
Also known as earth cave cold storage, caves are mostly arch structures, including single-hole type and multi-arch type. 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. Cold storage in caves
Generally, it is built in the rock stratum with hard rock and good integrity. The inside of the cave body is generally lined or sprayed with anchor, and the thickness of the rock stratum of the cave body is generally not less than 20m.
Composition of cold storage
Cold storage consists of two parts: warehouse building and refrigeration control. According to the different purposes of the building, it can be divided into four parts: cold working room and cold storage room, production auxiliary room, living auxiliary room and production auxiliary room.
Three, 1. Cold storage enclosure structure
The cooling capacity of cold storage through the enclosure is directly proportional to the unit heat flow of the enclosure. Therefore, efforts should be made to reduce the unit heat flow index of the cold storage envelope. To reduce the unit heat flow of the envelope, the thermal conductivity of the insulation material should be small, and the envelope layer should be thick. But the thickness should not be too thick, otherwise there will be problems such as increasing construction cost and wasting space. Therefore, the thermal insulation material should be selected within a suitable thickness range. Generally, thermal insulation materials are required to have low thermal conductivity, low water absorption, good low temperature resistance and low cost.
Commonly used cold storage insulation materials include rice husk, polystyrene foam, polyurethane rigid foam and so on. Rice husk is easy to obtain, but it has low thermal resistance, easy moisture absorption and large dosage. The construction of the warehouse is labor-consuming and time-consuming, and the cost is actually not lower than that of polystyrene. There are many manufacturers of polystyrene foam plastics, which are convenient to purchase, large in thermal resistance, moderate in price and convenient to build and install; Polyurethane vinegar rigid foam has the largest thermal resistance and the best thermal insulation performance, but the price is higher.
2. Moisture-proof and steam-proof of cold storage enclosure structure
The enclosure structure of cold storage should also take moisture-proof and steam-proof measures, otherwise the thermal insulation performance of thermal insulation materials will become worse. This is also the reason why the heat preservation performance of the cold storage body is good at first, but the heat preservation effect becomes worse after a period of time. Because water vapor permeates from the high temperature side to the low temperature side, the moisture-proof and vapor-proof layer should be located on the high temperature side of the insulation layer.
3. Evaporation pressure and temperature of cold storage
Evaporation temperature and evaporation pressure are corresponding. After knowing the evaporation pressure, the evaporation temperature can be obtained by looking up the table. Under the condition of constant cold storage temperature, the temperature difference (the difference between evaporation temperature and storage temperature) decreases, the evaporation temperature can be increased accordingly, and the refrigeration capacity of cold storage will be improved, that is, the cycle efficiency will be improved and the electric energy will be saved accordingly.
4. Refrigeration defrosting operation
Generally speaking, when the resistance of frost layer on the evaporator surface to air is not obvious and the air flow through the evaporator is not reduced, the influence of frost layer is not serious and defrosting is not necessary; When the air volume is obviously reduced, defrosting should be carried out. The greater the air humidity, the greater the temperature difference between the evaporator and the cold storage, and the easier it is to frost on the evaporator. Combined with fresh-keeping technology, packaging and refrigeration as far as possible can reduce the dry consumption of fruits and vegetables, reduce the defrosting times of evaporator, and actually play an energy-saving role in cold storage.
5. Cold storage temperature and cold storage utilization rate
Different fruits and vegetables have different storage temperatures, and each fruit and vegetable also has a suitable storage temperature range. Without affecting the quality of fruits and vegetables, the energy-saving refrigerator should choose a higher storage temperature. When the temperature of the cold storage is high, the evaporation temperature of the refrigeration system will also increase accordingly, the refrigeration capacity of the refrigerator will increase, and the cycle efficiency will certainly increase. More importantly, increasing the temperature of the cold storage can also reduce the heat transfer through the warehouse. The utilization ratio of energy-saving refrigerator warehouse is the ratio of the actual volume of fruits and vegetables to the effective volume of the warehouse. Generally, the volume utilization rate of mini-refrigerator should not be lower than 0.3, and of course it should not be too high, otherwise it will be difficult to cool down. When the volume of fruits and vegetables to be stored changes greatly, it should be divided into two or more cold rooms. In addition, it is self-evident that choosing a reasonable storage period is energy-saving for refrigeration.
Four, micro energy-saving refrigerator equipment main features:
(1) The refrigerant filling and debugging of mini energy-saving refrigerator have been strictly tested before leaving the factory. At the same time, the installation is convenient and fast. Just connect the indoor unit and outdoor unit with pipes and turn on the power supply to work.
(2) The refrigeration unit of mini energy-saving refrigerator adopts imported fully-enclosed refrigeration compressor, and the main control components can also adopt foreign products, which is safe and reliable in operation and has a long trouble-free operation time.
(3) The automatic control system of miniature energy-saving refrigerator is controlled by microcomputer, with accurate temperature control and simple operation. The unit has automatic and manual position operation functions, and is equipped with various automatic protection devices. At the same time, it is equipped with an electronic temperature display to facilitate users to observe the temperature in the cold storage.
(4) The mini energy-saving refrigerator unit adopts hot air or electric heating to defrost, which has short defrosting time and small temperature fluctuation in the refrigerator during defrosting.
There are two commonly used specifications of miniature energy-saving refrigerators: 90m3 and 120m3, and the construction investment is generally1.5 ~ 20,000 yuan. The warehouse built according to the design points of miniature energy-saving refrigerator has the advantages of fast refrigeration speed, good thermal insulation performance and small fluctuation of cold storage temperature, and the cold storage temperature can be reduced from 20℃ to 0℃ within 48 hours after the empty warehouse is turned on. In the pre-cooling stage of fruit, the daily power consumption of equipment is generally 40~50 degrees, and it is only 7~8 degrees after the temperature of cold storage is stable. Natural cold sources can be used to cool down in winter in northern China, and the monthly power consumption is very low.
Maintenance of refrigeration equipment
1, regularly check whether the power supply voltage meets the requirements, and the voltage should be 380 V 10% (three-phase and four-wire). When the cold storage equipment is not used for a long time, the main power supply of the cold storage should be cut off to ensure that the cold storage equipment is not affected by moisture and is not polluted by dust, ammonia and other substances.
2. The condenser on the refrigeration unit is easy to be polluted, so it should be cleaned regularly according to the actual situation. So as to keep good heat transfer effect. Good heat dissipation and refrigeration. Do not pile up sundries around the refrigeration unit;
3, electrical equipment of refrigeration equipment should avoid be affected with damp, so as to avoid electric shock accidents caused by leakage.
4. The hinge, handle and lock of the refrigerator door should be lubricated regularly according to the actual situation.
5, electrical equipment maintenance refrigeration equipment should be operated by an electrician or someone who knows the knowledge of electricity. Any maintenance must cut off the power supply to ensure safety.
6. Vibration should be avoided during the operation of the refrigerator, which will not only increase mechanical wear, but also cause the connecting pipe on the unit to be loose or broken. If abnormal noise is found during the operation of the machine, stop the machine to check and eliminate it before running. The protection function of the refrigeration compressor set has been preset, and no adjustment is needed.
7. Regularly check whether the connecting pipes of the refrigeration unit and the connecting pipes on the valve parts are firm and whether there is refrigerant leakage (generally, there will be oil stains where leakage occurs). The most practical leak detection method is: dip sponge or soft cloth in detergent, rub out foam, then evenly spread it on the place to be detected and observe for a few minutes. If it leaks, bubbles will appear. Mark the leak, and then fasten or gas welding (maintenance operation should be carried out by professional refrigeration personnel).
8. sundries shall not be piled on the top (roof) of the cold storage equipment, otherwise the storage board of the cold storage will be deformed, which will affect the thermal insulation performance, and the channels around the cold storage should be kept clear. Only by ensuring good heat dissipation can refrigeration be good. The location of the cold storage should be kept dry and clean, free of inflammable and explosive articles, and ensure no potential safety hazard. Articles shall not be stacked in front of the evaporator (a certain gap shall be left), so as not to affect the refrigeration effect. 9. If the air humidity is too high, the defrosting interval is long, and the storage temperature setting is abnormal, all these will cause the frost layer on the evaporator to thicken during storage, and the storage temperature will not drop. Defrosting (defrosting) should be carried out at this time. Observe in time, and stop defrosting immediately after the frost layer disappears. Please wait a moment before starting the equipment.
10, the parameters such as temperature and temperature difference in cold storage equipment should be set according to the actual situation of cold storage, and the parameters should not be changed at will. The cold storage has been customized according to the user's requirements when it leaves the factory. Before setting parameters on the controller, it is necessary to know the technical parameters of the cold storage.
1 1. The compressor should be started frequently, and the shutdown interval should not be less than 6 minutes. When it is found that the oil level of compressor mirror drops or becomes dirty, it needs to be added or replaced in time. Unqualified refrigerating machine oil with wrong brand and high water content after long-term exposure to air cannot be added, otherwise it will cause high-temperature carbonization, low-temperature wax precipitation, motor insulation damage and system oil return difficulty. Always pay attention to the temperature changes of compressor shell, fuselage and cylinder head to determine whether the compressor is operating normally. Refrigeration and compression devices do not need to be refueled under normal circumstances. If it is determined that refueling is needed, the special oil for compressor shall be added by professionals, and the refueling amount shall be determined by professionals. Blind addition is not allowed.
12, regularly check whether the power supply voltage is normal (three-phase, four-wire), and check whether the power supply master brake protection function is normal and effective.
How to choose a suitable cold storage
Dear users, if you want to build a suitable cold storage, Capgemini Refrigeration suggests that you consider the following aspects:
1. Determine the size (length× width× height) of the cold storage according to the tonnage of the stored goods, daily incoming shipments and the size of the building, and determine the specifications and dimensions of the warehouse door and the opening direction of the door. The installation environment of cold storage should be clean, dry and ventilated.
2. According to the stored articles, select and determine the temperature in the warehouse (fresh storage: +5-5℃, cold storage: 0- 18℃, low temperature storage:-18-30℃).
3. According to the characteristics of your own building and the local water source, choose the refrigeration mode of the refrigerator, which generally includes air cooling and water cooling. (Users of air-cooled refrigerators only need to choose the installation location, and users of water-cooled refrigerators also need to configure the installation locations of pools or deep wells, circulating water pipes, pumps and cooling towers).
I hope I can help you, please adopt!