The tubes of the tube-and-tube heat exchanger can be ordinary carbon steel tubes, stainless steel tubes, aluminum tubes or copper tubes. The heat exchanger is exposed to water and organic impurities for a long time during the working process, and the tube is corroded seriously. The use of stainless steel tube can effectively prevent corrosion, the tube wall is not easy to scale, easy to clean, the heat transfer coefficient is higher, and the extension of the service life also makes up for the disadvantage of higher price. For condensers of the same area, the difference in tube material and cooling medium flow rate has a significant impact on the heat transfer coefficient.