Can be seen from Table 1, several indicators of cooling water quality than the groundwater quality standards (GB/T14848293) class Ⅱ standard even higher [4], while the supply of water quality standards even to the class Ⅰ criteria, indicating that cooling water Requirements are relatively high. If the direct use of groundwater as cooling water, the water temperature low and stable, so even to energy saving, but high hardness cooling water fouling coefficient of the condenser will increase the amount of change in the case of cooling, cooling tower treatment Would increase the amount of water [5].
 2 problems in cooling water system
　　2.1Scaling
Cooling Water for general use tap water, and some units for energy use deep well water, whether tap or well water, have a certain hardness. If it is well water, hardness higher. In addition, the water generally comes from the south or through the limestone rock, so the hardness of the water higher than the North [5]. Scaling in cooling water system to produce another reason is the water temperature is dynamic, especially in the case of large load fluctuation, the temperature change will accelerate the formation of scale. The cooling water is very hard to run for some time, heat transfer in the condenser water in brass or large scale production, mainly in the water the following reaction occurred due to calcium carbonate.

　　Ca(HCO3)2
　　vCaCO3+CO2+H2O(1)
Cooling water system in order to prevent scaling, multi-electronic processing of the current methods (including static treatment, electromagnetic polarization, high-frequency magnetic field, etc.). However, if the number of magnetic water heater installation design and installation position is unreasonable, will have serious corrosion of water systems, this negative effect is much larger than a positive effect on air conditioning and water system causing serious harm. Such as Shanghai Plaza, a 30-storey building with central air conditioning all imported, the design sector in the water system designed and installed more than 10 electromagnetic water processor, running no longer take other water treatment. Equipment to run only a year and a half had serious corrosion. After testing water samples, water Cu2 + ion concentration up to 50mg / L, Fe2 + up to 200mg / L.

2.2Corrosion
 Corrosion of the cooling water system are mostly electrochemical corrosion, corrosion of pipe walls of the condenser or the water of dissolved oxygen factors, pH, the ion content.

　　Anode: FevFe2 + +2 e,
       Cathode: 1/2O2 + H2O +2 ev2OH-(2)
Yin and Yang of reaction generated Fe (OH) 3 is usually generated by the rust, and general eye to see the rust is Fe2O3? nH2O, also called water iron oxide. If the condenser cooling water system is copper, when the presence of Cu2 + in water, even very low concentrations in water, but it is the cathode reaction of the depolarizing agent, and thus significant role in promoting corrosion.

　　阳极:FevFe2++2e阴极:Cu2++2evCu(3)
With the increase of Cu2 + concentration, the corrosion reaction intensified, and finally to copper corrosion perforation. In general, if the added inhibitor (passivation), or by electromagnetic treatment, corrosion problems can be solved, that is not very serious corrosion problems.

　　2.3Sludge and algae
 As the cooling water temperature right, easy to breed a lot of bacteria, microbes and algae. At present, many chillers are installed decontamination Y-filter, cooling water pump installed in the entrance of the riser. The Y-type filters can only capture the beginning of construction waste equipment operation, to prevent the waste into the condenser, can not be captured in the daily operation of small scale and rust, it will cause the condenser fouling, integrated mud and other impurities. In addition, a great number of central air conditioning units at the lowest cooling water system are not quick drain valve installed, some units also had stopped with the closure of these outfalls, in fact, this is wrong, and easy to make the accumulation of sludge within the refrigeration unit and impurities Affect the heat exchange efficiency. Where the use of electromagnetic water treatment cooling water system required to install sewage pipes, continuous emissions, emissions can be controlled in the loop water is about 0.5% to 1.0%. Open cycle cooling water system, have set up filters, filters filtering capabilities, according to the local atmospheric dust content, etc., may be considered by circulating water of 1% to 5% or with the actual situation to choose to get better Treatment effect. The other newly installed cooling water system or has been completely cleaning the cooling water system, you can also discharge every 1 to 2 weeks time.