Topics:
- General
- Operation
General:
An accumulator in the air conditioning system has the tasks of converting the last liquid droplets of the refrigerant into gas, removing moisture from the refrigerant, and adding oil. The accumulator is mounted on the low-pressure side of the system, between the evaporator and the compressor. The accumulator is only installed in air conditioning systems with a capillary tube. (The other version is with a TEV valve, but there is no accumulator, rather a filter/drier installed). The task of the capillary tube is to lower the system’s pressure, causing the refrigerant to evaporate. Unfortunately, the capillary is not always capable of converting all the refrigerant from liquid to vapor. There are always some liquid droplets that remain and then end up in the accumulator via the low-pressure part of the system. In the accumulator, these droplets are evaporated. It is very important that all liquid droplets have evaporated before the refrigerant reaches the compressor. Too large an amount of liquid causes the compressor to suffer from what is called ‘liquid slugging’ and it can be damaged as a result. After all, liquid cannot be compressed. The accumulator is often also mounted near warm engine parts. Therefore, the accumulator is internally heated, allowing the evaporation of the liquid droplets to proceed faster.
Operation:
The refrigerant enters the top of the accumulator from the evaporator. The present droplets and oil fall to the bottom and end up in the liquid reservoir. The vapor stays in the upper part before being drawn through the central tube by the compressor (due to suction). At the bottom of the accumulator is a desiccant that functions the same as a filter/drier in a TEV system. The present moisture is absorbed by the desiccant. The existing oil (the lubricating oil for the compressor) gradually sinks through the desiccant and collects at the opening, at the bottom of the tube. The oil is gradually drawn in by the venturi effect, as the gases in the tube move outwards (thus creating suction at the opening). In this way, oil is gradually added to the refrigerant, as too much oil can also cause damage to the compressor.
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