Optimal airflow for cooling compressors
Does a compressor need to be cooled?
Year after year, on hot days in summer, thousands of compressors in ice cream parlors, butcher shops and refrigerators of food dealers die of heat. The damage caused by this is immense: not only the technical damage to the compressor has to be borne. Significantly greater are the financial losses due to spoiled refrigerated goods and consequential costs due to loss of sales.
Every refrigeration plant engineer knows the problem: Every compressor needs fresh air for cooling, because compressors only work optimally up to a certain temperature. If this temperature range is exceeded, there is a risk that the overheating protection of the compressor will shut it down or, even worse, that the compressor will be damaged.
With simple means, it is possible to cool a compressor and ensure its proper functioning even on hot days.
The most cost-effective cooling medium is fresh air from outside. If the supply of fresh air is ensured and is available in sufficient quantities, it only needs to be conveyed in such a way that the removal of excess heat is ensured. It is important here that the cooling air that is to cool the compressor is also concentrated where the heat is generated: at the compressor to be cooled.
The following examples illustrate how the external air for compressor cooling is optimally conveyed:
High-pressure axial wall fans, e.g. the models of the EQ series in exhaust-air mode create sufficient negative pressure to allow the fresh air to flow. Ideally, both the supply air opening and the exhaust air opening are located on an exterior wall. The exhaust air opening is equipped with a high-pressure axial wall fan. The compressor is arranged so that it is located directly at the supply air opening, since this is where the highest air velocity of the fresh air prevails. It is advisable to place it on the north or east side of the building. The incoming cooler air bypasses the compressor and removes the excess heat through the exhaust air opening. The supply air opening should be dimensioned so that a velocity of approx. 4 – 5 m/s prevails in the supply air opening (see also: Calculation of air velocity). This can be easily closed against the penetration of small animals, leaves and dirt by a protective grille with wire mesh. If the opening is to be covered in a more architecturally sophisticated and aesthetic way, an aluminum weather-protection-grille from the ASWG series is recommended.
However, in this case, the strömung of the air should be taken into account. In the worst case, the room will be ventilated without absorbing the heat that the compressor discharges
.Wrong: The air flows directly from the inlet to the fan. The heat is only marginally removed. The compressor must be placed in the fresh air stream.
Wrong: Again, the compressor is not bypassed by the fresh air. The compressor must be placed in the fresh air stream.
Right: The compressor sits near the fresh air intakeöf opening. Here and directly at the exhaust fan is the höchste air speed and the Kühung of the compressor is optimal.
Right: Since the compressor sits in the middle of the room, a ventilation duct/Lüftungsrohr was used to supply the cooling fresh air. Achtung: Druckverlust Rohr beachten!
Right: The compressor sits centrally in the room, the supply airöffnung laterally. By means of Lüftungsrohr/ -channel, the fresh air is fed to the compressor and umspült this optimally.
If the amount of supply air is now still sufficiently dimensioned, even a hot summer day no longer poses a danger to the compressor, since the cooling of the compressor is guaranteed. However, the exhaust fan always runs at full load. In order to switch on the fan only when necessary and to regulate the speed depending on the temperature, a temperature control for fans is ideal.
Other relevant topics:
» temperature-dependent-control-of-fans-in-steps