The surface of the evaporator of the cold storage refrigeration system is easy to frost during use, and the presence of the frost layer worsens the heat transfer and reduces the refrigeration efficiency. The operating time of the refrigeration unit is extended, and the operating cost is artificially increased. Therefore, removing frost on the surface of the evaporator is one of the necessary energy-saving tasks in the cold storage on a daily basis. Cold storage defrosting methods: hot gas defrosting (hot fluoride defrosting, hot ammonia defrosting), water spray defrosting, electrical defrosting, mechanical (manual) defrosting, etc.
1. Hot gas defrosting
It is suitable for defrosting of large, medium and small cold storage drain pipes to directly enter the evaporator without interception, and the temperature of the evaporator rises, prompting the frost layer and the joint of the cold exhaust to melt or then peel off. Hot gas defrost is economical and reliable, easy to maintain and manage, and its investment and construction are not difficult. However, there are also many solutions for hot gas defrosting, the usual practice is to send the high-pressure and high-temperature gas discharged from the compressor to an evaporator to release the defrost, so that the condensed liquid enters another evaporator to absorb heat and evaporate into low-temperature and low-pressure gas, and then return to the compressor suction port to complete a cycle.
2. Spray water to defrost
It is mostly used in large and medium-sized air coolers to defrost, and regularly uses room temperature water spray to cool the evaporator to melt the frost layer. Although the defrosting effect is very good, it is more suitable for air coolers, and it is difficult to operate for evaporation coils. The evaporator can also be sprayed with a solution with a high freezing temperature, such as 5% ---8% concentrated brine, to prevent frost formation.
3. Electrical defrosting
Electric heating tube frost is mostly used in medium and small air coolers; Heating wire defrost is mostly used for medium and small cold storage aluminum pipes. Electric heating defrosting, simple and easy to use for air coolers; However, for the case of aluminum row pipe cold storage, the construction difficulty of aluminum fin installation heating wire is not small, and the failure rate in the future is relatively high, maintenance and management are difficult, economy is poor, and the safety factor is relatively low.
4. Mechanical artificial defrosting
Small cold storage pipe defrosting is suitable for manual defrosting of cold storage pipe is more economical, and the most original defrosting method. Artificial defrosting for larger cold storage is unrealistic, it is difficult to operate with the head up, the physical energy consumption is too fast, and the detention time in the warehouse is too long to harm the health, and the defrosting is not easy to be thorough, which may cause the deformation of the evaporator, and may even smash the evaporator and cause the refrigerant leakage accident.
