Why defrost cold storage What are the ways to defrost I. Overview: The frost on the surface of the evaporator in the cold storage hinders the conduction and distribution of the cooling capacity of the refrigeration evaporator (pipe), which ultimately affects the cooling effect. When the thickness of the frost layer (ice layer) on the surface of the evaporator reaches a certain level, the refrigeration efficiency even drops below 30%, resulting in a large waste of electrical energy and shortening the service life of the refrigeration system. Therefore, it is necessary to carry out the defrosting operation of the cold storage in an appropriate cycle. Second, the purpose of defrosting: 1. Improve system cooling efficiency; 2. Guarantee the quality of frozen products in the warehouse; 3. Save electricity; 4. Extend the service life of the cold storage system. 3. Defrosting method: Cold storage defrosting methods: hot gas defrosting (hot fluorine defrosting, hot ammonia defrosting), water spray defrosting, electrical defrosting, mechanical (manual) defrosting, etc. 1. Hot gas defrosting-suitable for large, medium and small cold storage row defrosting: Directly enter the hot high-temperature gaseous condensate into the evaporator without interception, and the temperature of the evaporator rises back, which promotes the melting or subsequent flaking of the frost layer and cold discharge junction. Hot gas defrosting is economical and reliable, maintenance and management are convenient, and its investment and construction are not difficult. 2. Water spray defrosting-mostly used for defrosting of large and medium-sized air blowers: Regularly spray cooling evaporator with normal temperature water to melt the frost layer. Although the defrosting effect of water spray defrosting is very good, it is more suitable for the air cooler, and it is difficult to operate for the evaporative coil. The evaporator can also be sprayed with a solution with a higher freezing temperature, such as 5% to 8% concentrated brine, to prevent frost formation. 3. Electric heating defrost-electric heating tubes are mostly used for small and medium-sized air blowers: Electric heating wire is mostly used for electric heating and defrosting of aluminum row tubes in small and medium-sized cold storage. It is simple and easy to use for air coolers and convenient to use; but for aluminum row tube cold storage, the construction of aluminum fins to install electric heating wires is not difficult, and The future failure rate is relatively high, maintenance and management are more difficult, the economy is also poor, and the safety factor is relatively low. 4. Mechanical and manual defrosting——Applicable to the defrosting of small-scale cold storage pipes: Manual defrosting of cold storage pipe is more economical and the most primitive defrosting method. Larger cold storages are not practical to use manual defrosting, it is difficult to raise their heads, the physical energy consumption is too fast, and staying in the storage for too long is harmful to the health of the body. Defrosting is not easy to complete, which may cause the evaporator to deform or even damage the evaporation. The device caused a refrigerant leakage accident. Fourth, the choice of fluorine system defrosting method:
Choose a relatively suitable defrosting method according to the evaporator of the cold storage. A small number of micro-cold storage use the storage to open the door and use the air heat to defrost naturally. Some high-temperature storage coolers choose to stop the refrigerator, turn on the cooler fan separately, use the fan to circulate air to defrost, and do not enable the electric heating tube to achieve the purpose of energy saving. 1. Defrosting method of air cooler: (1), there are electric heating tube defrost and water flushing frost can be selected, areas with more convenient water can prefer water flushing frost cooling fan, and water shortage areas prefer electric heating tube defrosting chiller. (2), electric heating tube defrosting is mostly used for defrosting of small air-conditioning fans; water-blowing defrosting air-conditioning fans are generally configured in large air-conditioning and refrigeration systems. 2. The defrosting method of the steel row: there are hot fluorine defrosting and manual defrosting to choose. 3. The defrosting method of the aluminum row tube: there are hot fluorine defrosting and electric heating defrosting to choose. Fifth, the cold storage defrosting time: Most of the cold storage defrosting is controlled according to the defrosting temperature probe or defrosting time. The defrosting frequency, time, and defrosting stop temperature should be adjusted according to the quantity of stacked goods and the quality of the goods. At the end of the defrosting time, and then to the dripping time, the fan starts again. Note that the defrost time should not be set too long, try to achieve a reasonable defrost. (The defrost cycle is generally based on two types of power transmission time or compressor start-up time.) VI. Reason analysis of excessive frost: There are many factors that affect frost formation, such as: evaporator structure, atmospheric environment (temperature, humidity), and air flow rate. The magnitude of the impact on frost formation and air cooler performance are: 1. The temperature difference between the inlet air and the cold storage fan; 2. Humidity of inhaled air; 3. Fin spacing; 4. Inlet air flow rate. When the temperature of the warehouse is higher than 8°C, the normal cold storage system hardly frosts; when the ambient temperature is -5°C to 3°C and the relative humidity of the air is high, the air cooler is prone to frost; when the ambient temperature decreases, due to the air The moisture content in the medium decreases and the frosting speed decreases instead.
