Solutions to common problems in cold storage installation, maintenance and use

Update:10 Sep 2021
Summary:

Solutions to common problems in cold storage installati […]

Solutions to common problems in cold storage installation, maintenance and use

1. The refrigeration compressor unit has no vibration reduction installation, or the vibration reduction effect is not good

According to the installation specifications, the overall vibration damping device of the machine group should be installed. If the vibration is not standardized or there is no damping measure, the machine will vibrate violently, which will easily cause pipe cracking, equipment vibration, or even machine room vibration.

2. There is no or lack of oil return bend in refrigerant pipeline

When the pipeline conveying refrigerant turns from lateral to upward bend, it must be made into a small bend that first sags down and then upwards, that is, a U-shaped bend, so that the pipeline is qualified if it goes upward, and it cannot be directly turned upward by 90 degrees. Otherwise, the oil in the system will not be able to return to the compressor well, and a large amount of oil will be deposited in the air cooler, which will make the fan and the entire system not function properly, or even damage the fan and unit equipment.

3. Unbalanced refrigerant pipe connection

When the unit pipeline is connected to a group of multiple compressors, in order to distribute the oil return to each compressor in a balanced manner, the main pipeline interface must be set in the middle of the multiple heads, and then branch pipes should be installed on both sides. To allow the return oil to flow into multiple compressor branch pipes in a balanced manner. Moreover, each branch pipe should be equipped with valves to adjust the amount of oil return.

4.The pipeline is not insulated

If there is no insulation material, the cold pipe will be frosted at the ambient temperature, which will affect the cooling effect, increase the load of the unit, and then make the unit super-intensive operation and reduce the service life of the unit.

5. Various technical indicators should be checked regularly and adjusted in time

The operating temperature and pressure of the system, the amount of lubricating oil and refrigerant, must be checked and adjusted in time. The system should have automatic control and compressor alarm devices. Once there is a problem, an alarm will be issued, or an automatic protective shutdown and the compressor will stop.

6. Maintenance of the unit

The lubricating oil and filter should be replaced regularly. Replenish refrigerant as needed. The condenser should be cleaned at any time and kept clean to avoid dust, sand or flying debris, which will affect the cooling effect. When the lubricating oil has been running for a long time under high temperature in the system, its performance may have changed and it cannot play the role of lubrication as it should. The filter should also be replaced regularly. We know that general machines have "three filters" and they must be replaced regularly.

7. The installation environment and maintenance of the air cooler

The location and environment of the air cooler inside the cold storage will affect its operation. Generally, the air cooler near the cold storage door is prone to condensation and frost. Although the air cooler can automatically heat and defrost at regular intervals, if the door is opened too frequently, the opening time is too long, and the time and quantity of hot air entering is long, the defrosting effect of the fan is not good. Because the defrosting time of the air cooler cannot be too long, otherwise the cooling time will be relatively shortened, the cooling effect will not be good, and the storage temperature cannot be guaranteed.

8.Drainage of melted water during defrosting by air cooler

This problem is related to the severity of the frosting. Due to the severe frost of the fan, a large amount of condensate will inevitably be produced. The fan's drain pan cannot bear it, and the drainage is not smooth, and it will leak and flow to the ground in the warehouse. If there are goods stored underneath, the goods will be soaked. In this case, a thicker draft tube can be installed to remove the condensate.
Some air coolers have the problem of blowing water from the fan and spraying it on the stock in the warehouse. This is also the frosting problem of the fan in the cold and heat exchange environment, mainly due to the condensed water generated by the fan leaf in the hot environment, rather than the problem of the defrosting effect of the fan itself.

9. Condenser fan motor and air cooler electric heating pipe problem

This is a vulnerable part. The fan motor that runs for a long time in a high temperature environment may malfunction and be damaged. If the guaranteed temperature of the cold storage is very important, some vulnerable parts should be ordered for timely maintenance.

10. The problem of cold storage temperature and cold storage door

A cold storage room, the area, the amount of inventory, how many doors are opened, the time and frequency of opening and closing of the doors, the frequency of inventory in and out, and the throughput of goods are all factors that affect the temperature in the warehouse.  
The design and construction of cold storage and the setting and quantity of cold storage doors must be comprehensively arranged according to the inventory and the frequency of opening and closing the doors. Cold storage users should also use cold storage reasonably according to design specifications, and cannot ignore design conditions and actual conditions of facilities, blindly increase inventory and increase cargo turnover, exceeding the normal load and bearing capacity of facilities and equipment. Otherwise, many problems will arise.

11.The fire safety problem of cold storage

The cold storage is generally around minus 20 degrees. Due to the low ambient temperature, it is not suitable to install a fire sprinkler system. Therefore, more attention should be paid to fire prevention in cold storage. Although the ambient temperature of the cold storage is low, if a fire occurs, there are combustibles in the storage, especially the inventory is often packed in cartons and wooden boxes, which is easy to burn. Therefore, the risk of fire in cold storage is also great, and fireworks must be strictly prohibited in cold storage. At the same time, the air cooler and its wire box, power cord, and electric heating pipe must be checked frequently to eliminate electrical fire hazards.

12.The ambient temperature of the condenser

The condenser is generally installed on the roof of an outdoor building. In an environment with a high temperature in summer, the temperature of the condenser itself is very high, which increases the operating pressure of the unit. If there is a lot of hot weather, you can add a pergola on the roof condensation to block the sun and reduce the temperature of the condenser, so as to reduce the pressure of the machine, protect the unit equipment, and ensure the temperature of the cold storage. Of course, if the unit capacity is sufficient to ensure the storage temperature, there is no need to build a pergola. 

13.The problem of low compressor efficiency

Due to the long-term operation of the compressor, the cylinder liner, piston ring and other parts will be severely worn and the fitting clearance will increase, and the sealing performance will be correspondingly reduced. The air delivery coefficient of the compressor will also be reduced, and the cooling capacity will be reduced. The refrigeration capacity of the compressor can be roughly judged by observing the suction and discharge pressure of the compressor. If the refrigeration capacity of the compressor drops, the common method is to replace the cylinder liner and piston ring of the compressor.

14.There is more air or refrigerating oil in the cold storage evaporator

Once more refrigerating oil is attached to the inner surface of the heat transfer tube of the cold storage evaporator, its heat transfer coefficient will be reduced. Similarly, if there is more air in the heat transfer tube, the heat transfer area of ​​the evaporator will decrease, and the heat transfer coefficient will decrease. The thermal efficiency will also drop significantly, and the temperature drop of the warehouse will slow down accordingly. Therefore, in daily operation and maintenance, attention should be paid to timely removing oil stains on the inner surface of the heat transfer tube of the evaporator and exhausting the air in the evaporator.

15.Improper adjustment or blockage of the throttle valve of the cold storage, and the problem of the refrigerant flow being too large or too small

When the throttle valve is opened too large, the refrigerant flow is too large, the evaporating pressure and evaporating temperature will also increase, and the temperature drop rate of the warehouse will slow down; at the same time, when the throttle valve is opened too small or blocked, the refrigerant The flow rate also decreases, the cooling capacity of the system also decreases, and the temperature drop rate of the warehouse will also slow down.
   Generally, it can be judged whether the refrigerant flow rate of the throttle valve is appropriate by observing the evaporating pressure, evaporating temperature and frosting of the suction pipe.
  Clogging is an important factor that affects the flow of refrigerant. The main cause of throttling valve blockage is ice blockage and dirty blockage.
  Ice blockage is due to the poor drying effect of the dryer. The refrigerant contains moisture. When it flows through the throttle valve, the temperature drops below 0°C. The moisture in the refrigerant freezes and blocks the throttle valve hole.
   Dirty blockage is caused by the accumulation of more dirt on the inlet filter of the throttle valve, and the flow of refrigerant is not smooth, resulting in blockage.