1、 The hazards of water ingress into refrigeration units

1. Ice blockage phenomenon: When moisture enters the refrigeration system and mixes with the refrigerant, it may form ice cubes due to the decrease in temperature when passing through throttling devices such as expansion valves or capillary tubes, causing ice blockage. In this case, the flow of refrigerant is obstructed, resulting in poor liquid supply and affecting the normal operation of the entire system.

2. Emulsified water in lubricating oil may cause the oil to emulsify upon contact, greatly reducing its lubrication performance and subsequently affecting the efficiency and lifespan of compressors and other moving parts.

3. Corrosion: Moisture in the refrigeration system can react chemically with the refrigerant to produce corrosive substances such as hydrochloric acid and hydrogen fluoride. These substances can cause severe corrosion to metal components, especially key parts such as valves, bearings, and shaft seals, shortening the service life of equipment and increasing maintenance costs.

4. The presence of moisture may also reduce the electrical insulation performance of refrigerants, which can be fatal for fully enclosed compressors as it may increase the risk of motor burnout.

5. System stability issues: Excessive moisture can also lead to abnormal internal pressure in the system, such as an increase in pressure on the high-pressure side, which not only increases the workload of the compressor but may also trigger the action of the high-pressure protection device, resulting in unit shutdown.

2、 Reference for Water Treatment Methods in Refrigeration Systems

Add a small amount of fluorine to the leakage area of the condenser and pressurize it with nitrogen to a pressure of 10kg. Use soap water and clean water to check for possible leaks. If it is the leakage part of the evaporator, observe whether there are oil stains in the chilled water. If there are, there will be leakage; if not, there will be no leakage. If the added refrigerant contains water, release an appropriate amount of refrigerant from the bottle into a clean and dry glass container. After the refrigerant evaporates, observe whether there is water in the container. If there is, it indicates that the refrigerant in the bottle contains a high amount of water and investigate the source.

If there is a lot of water entering the system, refer to the following treatment methods: 1. Disassemble the refrigeration system components: condenser, evaporator, compressor (remove the oil filter), high-pressure drying filter, expansion valve, solenoid valve, shut-off valve, liquid storage tank, connecting pipeline, etc. They can be disassembled (large components do not necessarily need to be moved) to facilitate the next step of work.

2. Segmented blowing: The method of instantly releasing water from the components after pressurization with nitrogen gas to blow out as much water as possible. If the refrigerant system pipeline is complex, according to the specific situation, a welding gun can be used to burn the pipeline in certain parts and then blow out the moisture in sections

3. Restoring the refrigeration system: After restoring the entire unit, open all the pathways in the refrigeration system (the valve core of the expansion valve, the high-pressure drying filter element, the valve core of the solenoid valve are temporarily not installed, and the oil filter and refrigeration oil in the compressor are temporarily not added), and use a longer time than usual to vacuum (preferably the components can be heated and the compressor can be connected to the oil heater to accelerate the evaporation of residual water in the system).

4. Start up operation: Confirm that the moisture in the system is basically eliminated, then restore the refrigeration system, install a clean oil filter, high-pressure drying filter element, add refrigeration oil, and follow the normal assembly steps of the unit.

Reference for processing methods for systems with limited water intake: If the water intake in the refrigeration system is not very severe, there is no need to disassemble the refrigeration components, just replace the filter.

1. Filter replacement: First, replace the high-pressure drying filter of the unit system. If it is a drying filter drum, clean and dry degreased gauze can be used to make a pocket, and then modified with "active alumina particles" and added with color changing silicone gel (for easy observation of moisture content). Replace the refrigeration oil that originally contained moisture in the compressor.

2. Replace the filter again: After running for a period of time, replace the dry filter again, pay attention to observing the color changing silicone gel to determine the degree of water content in the system, and repeat this operation sequence.

3. Start up operation: Confirm that the moisture in the system is basically eliminated, replace the clean oil filter, high-pressure drying filter element, refrigeration oil, etc., and follow the normal assembly steps of the unit.

3、 Case of water ingress in cold storage system

Many low-temperature systems in cold storage are equipped with heat recovery. In winter, in order to prevent low condensation pressure, the inlet, outlet, inlet, and return of heat recovery are closed. Shortly after opening the water and air valves in March, water droplets and mist were found on the sight glass of the unit's liquid storage tank, and it was realized that there was a leak in the heat exchanger. All valves were immediately closed.

Reason for the problem: After on-site analysis and dismantling inspection of the heat exchanger, the reason is that the water inside the heat exchanger was not completely drained (possibly related to internal dirt). Resulting in the failure to completely drain the water in the lower half of the heat exchanger. The water that has not been released from the lower half of the exchanger freezes in winter, causing the copper pipes inside the exchanger to swell and crack. When the heat exchanger is in use, moisture enters the refrigeration system.

Emergency solution: First, close all compressor suction and exhaust valves and oil circuit valves of the unit. Remove the filter cores of the liquid supply system and the return system, make filter sized bags with gauze, and put them into the filter bucket with absorbent silicone.

Start up operation: Start a compressor, open the cold storage system, and allow the refrigerant to circulate. If the expansion valve is found to be blocked, hot water or a hot air blower can be used to blow it open. And replace the silicone gel repeatedly every 2-4 hours to absorb the moisture in the system. After the overall operation is normal, replace the refrigeration oil, oil filter, and supply and return air filter element. If necessary, replace them twice.