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Removal of condensate water and air: In steam systems, condensate water is generated as a result of steam condensation, and air is present in the steam. The presence of these substances not only causes the problems mentioned below but also leads to issues such as corrosion of the equipment; therefore, they must be removed from the system promptly. Here, non-condensable gases such as carbon dioxide that coexist with steam are represented by air. 1) Reduction in heat transfer efficiency: The presence of condensate water and air forms a coating on the heat transfer surface of the heat exchanger, resulting in a decrease in heat transfer efficiency. Thermal conductivity of materials: The thermal conductivity of materials is expressed in W/m·°C. For air, it is 0.025; for condensed water, it is 0.5; for steel, it is 50; and for copper, it is 400. The values shown in the table represent the thermal conductivities of air, condensed water, steel, and copper. It indicates that the higher the value, the better the thermal conductivity; conversely, the lower the value, the worse the thermal conductivity. From the table, we can see that copper’s thermal conductivity is 8 times that of steel; therefore, using different materials for the heat exchange plates in heat exchangers results in varying heat exchange efficiencies. However, when air and condensate water are present, the adverse effects resulting from this are incomparable. The thermal conductivity of steel is only 1/2000 that of air, and that of condensed water is 1/100 of it. Assuming that a condensate film 0.1 mm thick forms on the heat exchange surface, it is equivalent to an increase in the thickness of the steel plate by 10.0 mm (0.1 mm × 100) ； If an air film of 0.1 mm is formed on the heat exchange surface, it is equivalent to an increase in the thickness of the steel plate by 200 mm (0.1 mm × 2,000). Assuming that the thickness of this steel plate is 10.0 mm, the heat transfer efficiency will decrease by 50% due to the presence of a condensation water film, while it will drop by up to 95% as a result of the formation of an air film. In other words, when the material of the heat exchange plate is copper, the formation of condensate water and an air film adds thicknesses of 80 mm and 1600 mm respectively, which are unrealistically large values in reality. Thus, the significant reduction in heat transfer efficiency caused by the presence of air and condensate water can be confirmed once again through this example. 2) The phenomenon of decreasing heating temperature: The presence of air not only reduces the heat transfer efficiency but also lowers the heating temperature. This reason can be understood through the \"Dalton’s law of partial pressures\". Its content is that \"when two or more different gases are mixed together, the pressure of the gas mixture is equal to the sum of the pressures of each gas within a certain volume.\" For example, if air at a pressure of 0.1 MPa is mixed into steam at a pressure of 0.4 MPa, the actual pressure of the steam will decrease to 0.3 MPa. Originally, a saturation temperature of 144°C at 0.4 MPa was required for heating in order to meet production requirements, but in reality heating was carried out at a saturation temperature of 134°C at 0.3 MPa. The pressure indicated by the gauge, at 0.4 MPa, is actually the sum of the pressure of steam and air; when this cannot be determined, it leads to poor quality in product processing. 3) Water hammer phenomenon: When condensate remains in the system, a destructive water hammer phenomenon, also known as the water hammer effect, may occur upon restarting the system. One of the causes of water hammer phenomenon is the high-speed flow of steam carrying along the stagnant condensed water; eventually, a large amount of this condensed water accumulates and forms a piston-like mass that causes impact at pipe bends or locations where valves are installed. It emits a knocking sound when a collision occurs, and may damage the installed valves and pipes.