Two Basic Problems of Refrigeration Systems
Refrigeration systems are made up of various components. For instance, compressors, condensers, refrigerant, and pumps. These systems are susceptible to problems. For example, a refrigeration unit may freeze up or malfunction. In this article, we’ll look at two basic refrigeration system problems.
Oil safety control tripped on refrigeration system
The oil safety control is a vital part of any refrigeration system. It acts as a safety device when the oil pressure drops below a set threshold. Generally, a reduction in oil pressure is expected to last for about sixty to ninety seconds. A faulty contactor may be the culprit.
One of the best ways to detect this condition is to look at the pump’s oil pressure. You can do this by measuring the crankcase pressure and subtracting it from the discharge oil pressure. This should produce a reading of zero volts. This is enough to actuate the oil safety control’s low-voltage relay.
A good rule of thumb is to never try and bypass the oil safety control. This will result in no back-up. The best way to avoid this nefarious practice is to ensure the controls are calibrated properly. A well-tuned system should not exhibit any repeat trips.
There are numerous variations of the oil pressure control, including those incorporating an electronic control module. A Copeland Sentronic is a good example of this class of controls. It has a number of notable improvements over its predecessors.
Low suction pressures and low gas velocities
In refrigeration systems, low suction pressures and low gas velocities are common problems. Both of these factors can lead to oil logging in the evaporator and compressor. Luckily, there are ways to correct them.
The most important thing to consider is the design of the system. The size and shape of the piping is very important, but so is the position of the equipment. The correct positioning can affect the amount of oil that is returned to the compressor.
If the suction pipe is sized properly, it should slope towards the compressor. This will allow smaller drops of oil to pass through the system. The velocity of the refrigerant is also an important factor. If it is too low, the liquid refrigerant will flow back to the compressor. This can create a flooded compressor or compressor oil leak.
Another reason for low suction pressures is poor insulation. This will limit the velocity of the refrigerant and may cause a poor condensing effect.
Frost or ice in the refrigerator
There are several reasons why frost or ice in the refrigerator could occur. Some are temporary and are not serious. Others are more serious and require repair. However, these problems can be easily solved. The first step is to understand what is wrong with your appliance.
If you see ice build up on the interior walls, it is probably a symptom of poor ventilation or improper door gaskets. These may cause excessive frosting of the evaporator coil.
Some appliances can be defrosted by using a drain heater. You can also wrap copper wire around the heating element. This will help conduct heat up and allow the evaporator to cool down.
One of the easiest ways to prevent ice buildup is to open the doors regularly. This allows warm air to enter the freezer compartment, which may result in a lack of cooling. If you can’t open the doors, make sure to keep a drip pan in place to catch any water that runs out.
Refrigerant migration
Refrigerant migration occurs when refrigerant vapor migrates from high pressure areas to lower pressure areas. The vapor can leave the suction line and enter the crankcase or other areas of the system. The refrigerant will continue to migrate until the pressure-temperature ratio of the refrigerant throughout the system is the same.
This can cause the compressor to fail. Refrigerant vapors condense in the crankcase with the oil in the shell of the compressor. The vapor will then be driven back into the suction line. This can lead to liquid slugging during start-up or compressor failure.
The key to preventing refrigerant migration is to ensure that the pressure and temperature of the refrigerant in the crankcase is higher than that in other parts of the system. This will reduce the chances of the refrigerant forming a striated layer in the crankcase during long off cycles.
It is also a good idea to use a pump-down circuit to help prevent refrigerant migration. This circuit uses a solenoid valve to cycle the refrigerant in the liquid line. This increases the displacement of the oil in the crankcase to help control the migration of the refrigerant.
