The accumulation of a layer of solids or sludge, called fouling, adds additional fouling thermal and flow resistance, increasing required heat exchange area, power consumption, and maintenance cleaning costs. Due to the large number and wide range of heat exchangers, heat exchanger scaling has a great impact on one-time investment, metal material consumption and energy consumption. Today, with the emphasis on energy conservation and emission reduction, it is particularly important to minimize the impact of dirt.

During the operation of the water-cooled chiller, there are minerals that are slightly soluble or insoluble in water, such as calcium carbonate, calcium sulfate, and silicic acid, on the water side of the heat exchange equipment, especially in the condenser of the open cycle cooling water system. Calcium, iron oxide, phosphate, etc. Scale adheres to the inner surface of the heat transfer tube; dust, silt, algae, microbial communities and even leaves, weeds, etc. The sediment mixed into the water is deposited on the inner surface of the heat transfer tube to form sludge. Water side dirt mainly includes scale and sludge. Dirt increases the heat transfer resistance of the heat transfer surface, directly affects the heat transfer effect, increases the condensation temperature or reduces the evaporation temperature, resulting in increased energy consumption and reduced cooling capacity of the refrigerator. The thickening of the scale layer reduces the cross-sectional area of ​​the flow in the heat transfer tube, increases the water flow velocity and the roughness of the tube wall, resulting in an increase in the flow resistance on the water side, thereby increasing the power consumed by the pump.

The accumulation of dirt will also cause local corrosion or even perforation of the heat exchange surface, seriously threatening the safe operation and service life of the water-cooled chiller. In the heat exchanger design of water-cooled chillers, the presence of dirt increases the heat transfer resistance, reduces the overall heat transfer coefficient of the heat transfer tube, and increases the energy consumption of the compressor. Therefore, it is necessary to compensate for the decrease in the total heat transfer coefficient by increasing the heat transfer area to ensure sufficient heat transfer. The correct choice of fouling coefficient has a great impact on the cost, energy consumption and operating costs of heat exchange equipment. Unfortunately, despite ongoing scientific research on fouling, to date there is no universally accepted fouling coefficient value that can be accurately used in heat exchanger design.

In the design of heat exchangers, the choice of fouling coefficient often relies on experience rather than science. Based on operating experience with a specific system with the same or similar operating conditions, or based on measurement data obtained from actual equipment with the same operating conditions, or based on test data obtained in testing with prototype or model equipment in the laboratory, or using recommendations from authoritative agencies The data are estimated to be reasonable.

Since the usage characteristics of heat exchangers in different regions and situations are different, the above method may not be suitable for heat exchangers in different situations. Before determining which method or methods to adopt, the process parameters, equipment materials, operating condition variation range, and fouling performance of the heat exchanger equipment need to be collected, tested, and analyzed. Therefore, the technical requirements for scale prevention and descaling are put forward, and the true way to save energy is to choose appropriate, effective, and economical scale prevention and descaling measures to ensure the normal, stable, and effective operation of heat exchange equipment.