Ventilation storage is developed on the basis of open cellars and semi-fixed cellars. It is a fixed building of brick, wood and cement structure, also called fixed pit. In the 50s and 70s of the 20th century, many buildings were built in major cities in northern China. Similar to the cellar pit, the ventilated storage tank also uses the principle of air convection to introduce fresh cold air outside the reservoir to remove hot and humid air and undesirable gases to cool the air. However, it has a better ventilation system and thermal insulation structure. The cooling and insulation effects are much higher than those in the cellar and can be used for a long time. In addition to storing Chinese cabbage, it can also be used to store potatoes, radishes, cabbage, onions, carrots, squash, and short-term storage for summer and autumn vegetables. (A) Types of Ventilation Stores: Ventilation storage stores can be divided into three types: aboveground, semi-underground, and underground. The above-ground library is all on the ground and is greatly affected by the temperature. Its air inlet is located at the bottom of the reservoir wall and the air outlet is located at the top of the reservoir. The two can have the highest height difference, which is conducive to the natural convection of the air and the ventilation effect. it is good. Underground reservoirs are all deep in the soil, and only the top of the reservoir is exposed on the ground. The insulation performance is good, but the height difference between the inlet and outlet is small, the air convection is slow, and the ventilation and cooling effect is poor. Half underground is somewhere in between. Because the ventilation warehouse is mainly used in autumn and winter, it is advisable to use the above-ground type in warm areas and underground type in cold areas. It is also possible to use semi-underground ventilation tanks of different depths depending on the climate and groundwater level in each place. The roof structure of the ventilation warehouse can be divided into three kinds: ridge roof, flat roof and dome. The earliest use of ridges was to use a large number of wood for herringbone beams, covering the surface with tiles, lining a layer of tightly packed reeds under the roof of the roof, or making a ceiling under the overhead frame, and covering the insulation material on the shed. Later, flat tops and domes appeared. The flat roof library is made of cement prefabricated plate racks on both sides of the wall, and some of them are made up of two rows of prefabricated plates, with the lower pillars and the center of the roof slightly ridged. In the 1970s, the dome-shaped library developed rapidly, dividing the single arch and the double arch. Arches are arched on the wall of the arch, which can be caused only by bricks and cement. The arched building transfers all the weight of the arch to the base walls on both sides. If the span is large, pillars may not be set up in the middle. low. Usually, a width of about 6m in width is built into a single arch, and a large-span double arch is built to reinforce the solidity. (II) Selection and layout of the site: The topography of the vegetable production area should be high-dry, the highest groundwater level should be below lm, and there should be good ventilation around the air, no pollution, and a reservoir for traffic, water and power. Ventilation storages are mostly rectangular or long strips and are better extended in the north and south. In order to facilitate management, the storage of each warehouse should not be too large. Generally, one warehouse is 30 to 40 meters long, 8 to 10 meters wide, and the area is about 250 to 400 meters. It can store 100,000 to 150,000 Chinese cabbages, and its height is generally 3.5 to 4 meters. If it is too low, it will reduce the storage and affect the air flow in the warehouse. When the total storage is large, a number of warehouses can be built to form a pool. In cold regions, most of the warehouses are divided into two rows, with corridors in the middle, warehouses and corridors perpendicular, and the library doors communicate with the corridors. The corridor has roofs and windows, which are 6 to 8 meters wide. They can pass through cars and have double doors at both ends. The corridor can act as a buffer to prevent sudden changes in the temperature of the reservoir caused by cold wind blowing directly into the reservoir. It can also be used for grading, packaging or temporary storage of products. Alternatively, each warehouse can be opened to the outside world without a common corridor. A buffer suite must be built outside the warehouse. In the warm area, the library group is better equipped with a single library door, and the library door ventilation can be used directly. The arrangement of warehouses is divided into two types: split-type and joint-type. The separate warehouses are not connected to each other and their performance is very poor. They are used as the skeleton of the warehouse and the weight of the top of the warehouse, and rely mainly on the thermal insulation layer for insulation. Sawdust, rice husk, slag, perlite, etc. are commonly used in ventilated storage. Still air has good thermal insulation properties, and hollow brick walls in which air does not flow can improve the insulation effect. The thickness of the insulation layer should be such that the thermal energy dissipated outside during the coldest period is about the same as the total heat source of the reservoir so that the reservoir temperature can be stabilized without falling too low. Insulation materials must be kept dry to have good thermal insulation. Once wet, the heat insulation effect is greatly reduced. The contrast between dry and wet soils, dry sand and wet sand can be seen, so the insulation of the storage Layers shall be provided with waterproof layers on both sides to prevent the insulation material from getting wet. (III) Use and Management of Ventilation Library Treasury and equipment disinfection and ventilation warehouses are permanent buildings. They are used for many years or all year round. After each storage is cleared, warehouses must be thoroughly cleaned and portable equipment should be moved outside the warehouse for daylight disinfection. The warehouse is fully ventilated and sterilized. Can be sprayed with 1%-2% formalin or bleach solution, or combusted with 5 to 10g of sulfur per cubic meter of the reservoir (addition of sawdust); ozone treatment, concentration of 40mg/m3, both disinfection and In addition to the role of odor. When disinfecting, various containers, racks, etc. can be placed in the warehouse, sealed and then ventilated after 24 to 48 hours. Walls, ceilings, vegetable racks, and bins, etc., are treated with lime slurry plus 1%-2% copper sulfate white. Each used container should be washed immediately, then soaked with bleach or 2% to 5% copper sulfate solution, dried for use. 2. Storage of storage and stacking ventilation warehouses is large. In addition to Chinese cabbage, other vegetables are sometimes stored. At this time, all kinds of vegetables should be stored in separate stocks. Do not mix in one library to control different temperature and humidity and avoid evaporation of different products. Sexual substances interact with each other. One week before the product is put into storage, it is necessary to conduct air management on the empty storage. When the temperature is high during the day, all ventilation equipment will be turned off and turned on at night to make full use of the cold night air to lower the temperature of the library in advance. Products should be pre-cooled as much as possible to reduce the field heat brought into the warehouse. However, the storage capacity of the ventilation warehouse is large. To avoid over-concentration of product storage time, it can be put into storage after the Chinese cabbage is harvested and trimmed. However, it should be noted that one library should not be too many people at a time and can be dispersed into several libraries at the same time. Can also be supplemented with artificial blasting, increase ventilation, can be installed in the exhaust outlet exhaust fan to pump out the library out of the library, than in the air inlet hair dryer blowing hair to the library is good, because the latter is in the wind The wind speed is very high and it is easy to dry the product. When the outside temperature is lower than 0 degree, the product will be frozen. The Chinese cabbage stored in the ventilation warehouse is used for rack storage or basket storage. The method has been introduced in "cellar storage". Radon is rarely used in ventilated storage. Because of the limited height of stacking and stacking, the height of the ventilated storage can not be fully utilized to reduce the storage, and its storage effect is not as good as shelf storage and basket storage. 3. The ventilation of the temperature and humidity management ventilation library is mainly subject to the temperature requirements, and its management method is basically the same as that of the aforementioned cellar cabbage. At the beginning of storage, it is generally required to increase the ventilation volume as much as possible in order to reduce the temperature rapidly. At this time, all vents, doors, and windows should be opened so that the reservoir door serves as the air inlet, and the top vents of the reservoir serve as exhaust outlets. Can be supplemented by mechanical ventilation or blast. As the temperature drops, the opening area of ​​the vent is gradually reduced. In the coldest season, close all the air inlets so that the air vents can serve as the inlet and exhaust, or shorten the air release time. At the beginning of storage, the ventilation volume is large, the humidity in the warehouse is sometimes insufficient, and the water can be sprayed on the floor of the reservoir, or the bottom of the wet cloth is immersed in the water basin; the humidity is too high in the cold season, and the air volume should be appropriately increased every day when the outside temperature is high. . China Agricultural Network Editor
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