Harm of dirt to circulating water system

There are a lot of calcium bicarbonate and magnesium bicarbonate soluble in water in cooling water. During the heat exchange process, crystallization precipitates and precipitates on the heat exchange surface, forming hard stone scale. The accumulation of dirt directly reduces the heat exchange efficiency of the condenser and increases the power consumption. Kotz, an American air conditioning expert, pointed out that when the thickness of fouling in condenser pipe is 0.3mm, the energy consumption of water chiller increases by 15%; when the thickness of fouling reaches 0.9mm, the energy consumption increases by 35%.

In addition, in the circulating water system, the range of water temperature and pH value is just suitable for the growth of a variety of microorganisms. There are three kinds of common and harmful microorganisms: algae, bacteria and fungi. Among them, algae accumulation on the packing will affect the mass transfer efficiency. The slime secreted by bacteria and the impurities suspended in the water will form slime deposits and attach to the tube wall. The biofilm will bite the wall of the condenser tube.

In general, fouling of the condenser tube can cause many hazards:

 1.Reduce heat exchange effect

Most of the heat exchange tubes are made of carbon steel, the thermal conductivity of carbon steel is 46.4 ~ 52.2w/(m.k), but the thermal conductivity of carbonate fouling is 0.464 ~ 0.697 w/(m.k), only about 1% of carbon steel. It can be seen that the thermal conductivity of scale or other deposits will be greatly reduced. Therefore, when scale or other deposits cover the heat exchange surface of the heat exchanger, the heat exchange efficiency of the heat exchanger will be greatly reduced.

2.Reduce circulating water

The sediment or microbial sludge covers the heat exchanger wall and even blocks the heat exchanger pipe, which makes the sectional area and water flow of the circulating water channel reduce, thus further reducing the heat exchange efficiency.


3.Reduce the use effect of water treatment agent

Sediments and microbial sludge cover the metal surface, which prevents the corrosion inhibitor, scale inhibitor and biocide in water from reaching the metal surface to play the role of corrosion inhibition, scale inhibition and sterilization, and some microorganisms will react with some water treatment agents, thus damaging and reducing the use effect of these agents.


4.Accelerated corrosion

The formation of deposit and microbial scale promotes the formation of concentration difference corrosion cell and the corrosion under the scale, thus accelerating the corrosion of metal.

5.Shorten the service life of the equipment

On the one hand, deposits and microbial slime cover the surface of the heat exchanger, which hinders the effective heat exchange of the equipment, so that the metal on the heat exchange surface is in a long-term high-temperature heat exchange load state, leading to metal fatigue. On the other hand, the occurrence of corrosion will lead to the thinning of the heat exchange tube wall of the equipment, especially the corrosion under the scale will lead to the perforation and leakage of the equipment, which makes the equipment The service life is shortened.


Effect of dirt on equipment

Parameter change of chiller

Harm of dirt to circulating water system

Small temperature difference:3.4°C                                   ↑Small temperature difference:1.5°C


Comparison before and after stabbing



Perspective photo



Dirt, rust, rust residue and biological slime produced by the continuous propagation of microorganisms, which make the cold capacity of pipe blockage decrease, waste electric energy, and even shut down the equipment, directly damage the equipment and shorten the service life of the equipment. Therefore, the treatment of air conditioning system dirt is urgent.

Harm of dirt to circulating water system