1. The foundation of the cold storage is affected by the low temperature, and the moisture in the soil is easily frozen. Due to the volume expansion of the soil after freezing, it will cause ground rupture and deformation of the entire building structure, which will seriously make the cold storage unusable. For this reason, in addition to having an effective insulation layer, the floor of the low-temperature cold storage must also be treated to prevent the soil from freezing. The bottom plate of the cold storage needs to stack a large amount of goods, and also needs to pass various loading and unloading transportation machinery and equipment, so its structure should be strong and have a large bearing capacity. Building structures are vulnerable to damage in low temperature environments, especially during periodic freeze and thaw cycles. Therefore, the cold storage installation materials and the construction of each part of the cold storage must have sufficient frost resistance.
2. During the installation of the cold storage, the diffusion of water vapor and the penetration of air should be prevented. When the outdoor air invades, it not only increases the cooling consumption of the cold storage, but also brings moisture into the storage. The condensation of moisture causes the building structure, especially the thermal insulation structure, to be damaged by moisture and freezing. Excellent sealing and moisture and vapor barrier properties.
3. During the installation of the cold storage, the cooling fan should choose the equipment that automatically controls the defrosting. The automatic control system should have a suitable and reliable frost layer sensor or differential pressure transmitter to sense the best defrosting time; there should be a reasonable defrosting procedure and a cooling fan fin temperature sensor to prevent excessive heating.
4. The position of the cold storage unit is as close as possible to the evaporator, and it is easy to maintain and has good heat dissipation. If it is moved out, it is necessary to install a canopy, and the four corners of the cold storage unit need to be placed with shock-proof gaskets. The installation level is firm, and it is not easy to be touched by people.
5. The radiator of the cold storage unit should be placed as close as possible to the cold storage unit. It is better to place it in the upper position of the cold storage unit. The radiator installation position should have the best heat dissipation environment. The tuyere should not be short-circuited and facing other windows (especially residential windows) and equipment. It should be 2M high from the ground and the installation level should be firm.
6. The copper pipes of the cold storage unit need to be wrapped through the insulation pipes and the wires in the same direction together with the air-conditioning cable ties, and the pipelines should be as straight as possible and fixed in sections.
7. In addition to tying up the wire with air-conditioning cable ties, it needs to be protected by corrugated hoses or cable grooves. The temperature display wires should not be placed close to the wires as much as possible.
8. Because the condenser and evaporator of the cold storage unit have been pressed and sealed in the factory, there should be pressure when opening the package, and you can check whether there is any leakage. The copper pipes should have dust sealing measures at both ends. It is sealed to prevent dust from entering the tube. The condenser, cold storage host, evaporator and copper tube are connected by welding method, and the interface is firm and beautiful. In order to maintain a certain low temperature in the cold storage, the walls, floors and flat roofs of the cold storage are laid.
9. Therefore, the installation project of quick-freezing cold storage is different from general industrial and civil buildings, and has its unique structure. The installation of cold storage generally prevents the diffusion of water vapor and the penetration of air. A certain thickness of thermal insulation material to reduce the heat from the outside world. In order to reduce the absorption of radiant energy from the sun, the exterior wall surface of cold storage is generally painted in white or light color. After the installation of the cold storage, a comprehensive electrical safety inspection of the system must be carried out to eliminate hidden dangers, including whether the terminals or connecting wire connectors are loose, aging, and whether the metal cover is stuck on the wire, etc.
10. For fully enclosed compressors and air-cooled compressors without oil sight glass and oil pressure safety device, the oil pressure safety protection device should be able to automatically stop when there is a shortage of oil. Excessive compressor noise, vibration or current may be related to lack of oil. It is very important to accurately judge the operating conditions of the compressor and system. If the ambient temperature is too low, some oil pressure safety devices may fail, which will cause the compressor to wear out.
11. The frequency of the defrosting cycle and the duration of each continuation also need to be carefully set to prevent the oil level from fluctuating or even oil shock. If the speed is too low, the lubricating oil will remain in the return gas pipeline, and the return gas speed will decrease when there is a lot of refrigerant leakage, and it will not be able to return to the compressor quickly.
12. The distance between the oil return bends installed in the cold storage should be appropriate. When the number of oil return bends is relatively large, some lubricating oil should be added. When the compressor is located higher than the evaporator, the oil return bend on the vertical return pipe is necessary. The oil return bend should be as compact as possible. The air return speed will be reduced, and the oil return pipeline of the variable load system installed in the cold storage must also be careful. when the load is reduced. Too low speed is good for oil return. In order to ensure the oil return under low load, the vertical suction pipe can use double riser. The lubricating oil installed in the cold storage can only be left in the pipeline, the oil return is less than the running oil, and the frequent startup of the compressor is beneficial to the oil return. Because the continuous operation time is very short, the compressor stops and there is no time to form a stable high-speed airflow in the return pipe, and the compressor will be short of oil. The shorter the running time, the longer the pipeline, the more complex the system, the more prominent the oil return problem.
13. If there is little or no lubricating oil, there will be severe friction on the bearing surface, and the temperature will rise rapidly within a few seconds. If the power of the motor is large enough, the crankshaft will continue to rotate, and the crankshaft and bearing surfaces will be worn or scratched, otherwise the crankshaft will be locked by the bearings and stop rotating. The same is true for the reciprocating motion of the piston in the cylinder. Lack of oil will cause wear or scratches. In severe cases, the piston will be stuck in the cylinder and cannot move.
14. If the piston installed in the cold storage leaks due to wear, etc., the return of the lubricating oil to the compressor casing does not mean that it returns to the crankcase. The pressure of the crankcase rises, and the oil return check valve is automatically closed due to the pressure difference. The lubricating oil returned from the return pipe stays in the motor cavity and cannot enter the crankcase. This is the problem of internal oil return. Will cause oil shortage. In addition to this kind of accident occurring in worn out old machines, the liquid start caused by refrigerant migration will also cause internal oil return difficulties, but usually the time is short, at most ten minutes. It can be observed that the oil level of the compressor continues to drop, and the internal oil return problem occurs. until the hydraulic safety device operates. The oil level in the crankcase quickly recovered after the compressor was shut down. The root cause of the internal oil return problem is the leakage of the cylinder, and the worn piston components should be replaced in time.
Post time: Nov-11-2022
