Precautions for construction and operation of cold storage

Precautions for construction and operation of cold storage

1. Matters needing attention during cold storage installation

　　 1. When installing a cold storage, in order to maintain a certain low temperature, a certain thickness of insulation material must be laid on the floor, walls and flat roof of the cold storage to reduce the heat introduced from the outside.

　　2. In order to reduce the absorption of solar radiation as much as possible, the outer wall surface of the cold storage is generally painted white or light color. Therefore, cold storage buildings are different from general industrial and civil buildings and have a unique structure.

　　3. When installing the cold storage, prevent the penetration of air and the diffusion of water vapor.

　　4. Keep moisture-proof and air-proof performance and good airtightness during cold storage installation. Because outdoor air entering the cold storage body will not only increase the cold storage capacity of the cold storage, but also bring moisture into the warehouse. The condensation of moisture causes the building structure, especially the insulation structure, to be damp and freeze damaged.

　　5. The structure of each part of the cold storage and the building materials of the cold storage must have sufficient frost resistance. Because the foundation of the cold storage is affected by the low temperature, the moisture in the soil is easily frozen. The volume expansion after the soil freezes will cause ground cracks and deformation of the entire building structure. If the damage is severe, the cold storage may even be unusable.

　　 2. Pay attention to the following points during cold storage operation:

　　 1. Regular inspection and maintenance of the enclosure structure

The maintenance of the cold storage structure should also attract everyone’s attention. Infrared detection is currently used in many industries. The so-called infrared thermal imaging camera detects infrared energy (heat) through non-contact and converts it into electrical signals. A detection device that generates thermal images and temperature values ​​on the display, and can calculate the temperature values. It can accurately quantify the detected heat, so that you can not only observe the thermal image, but also accurately identify the heating fault area And rigorous analysis.

　　 2. Drain the oil in time

　　 The oil attached to the surface of the heat exchanger will cause the evaporation temperature to drop and the condensation temperature to rise, so the oil should be discharged in time. Automatic control can be used, which can not only reduce the labor of workers but also control the precise time and amount of oil discharge.

　　3, defrost in time

The heat transfer coefficient of steel is generally about 80 times that of the frost heat transfer coefficient. If the evaporator surface is frosted, it will increase the thermal resistance of the pipeline, reduce the heat transfer coefficient and reduce the cooling capacity, so when the system runs for a period of time It should be defrosted in time to avoid unnecessary energy consumption of the system.

　　4. Prevent non-condensable gas from entering the pipeline

Since the adiabatic index of air (n=1.41) is greater than the adiabatic index of ammonia (n=1.28), when non-condensable gas exists in the refrigeration system, the discharge temperature of the refrigeration compressor will increase due to the increase in condensation pressure and compressed air. Studies have shown that: when non-condensable gas is mixed in the refrigeration system and its partial pressure reaches 0.2aMP, the power consumption of the system will increase by 18% and the cooling capacity will decrease by 8%.

　　5. Reasonable use of nighttime start-up time

(1) Effective use of peak and valley electricity at night. At present, our country implements different electricity tariffs according to the time of electricity consumption, and various provinces and cities have also adjusted according to the actual situation. The peak and valley are very different, and the cold storage consumes a lot of energy. You can use the night to run cold storage , Avoid the peak electricity consumption during the day.

　　 (2) Reasonable use of temperature difference between day and night my country has a large temperature difference between day and night. According to statistics, every 1°C drop in condensing temperature can reduce compressor power consumption by 1.5% and increase cooling capacity per unit shaft power by about 2.6%. At night, the ambient temperature is low, and the condensation temperature will also drop. According to the literature, the temperature difference between day and night in marine climates can reach 6～10℃, the temperature difference between day and night in continental climate can reach 10～15℃, and the temperature difference between day and night in southern areas can reach 8～12℃ , So increasing the nighttime start-up time is conducive to energy saving in cold storage.