The influence of heat exchange tube on heat exchange effect

The heat exchange tube is one of the components of the heat exchanger. Without the heat exchange tube, the heat exchange process of the heat exchanger cannot go on. Therefore, the selection of the heat exchange tube will directly affect the heat exchange efficiency and heat exchange of the heat exchanger. Effect. So, how do different heat exchange tubes affect the heat exchange effect?

1. The material of the heat exchange tube will affect the heat exchange effect. Commonly used heat exchange tube materials are: carbon steel(such as seamless carbon steel heat exchange tubes), low alloy steel, stainless steel, copper, copper-nickel alloy, aluminum alloy, titanium, etc.; in addition, there are some non-metallic materials, such as graphite, ceramics, and polytetrafluoroethylene. Since most of the media to be transported in the heat exchanger are hot water or corrosive liquids, if the copper tube heat exchange tube is selected, the copper tube’s oxide layer will increase with the increase in the use time of the copper tube The thicker the thickness, the more and more dirt inside, the worse the heat transfer effect, and the stainless steel will basically not oxidize, even if it oxidizes more slowly; in addition, according to the law of thermal conductivity and thermal resistance, the thermal conductivity does not change, and the wall The smaller the thickness of the tube, the smaller the thermal resistance and the greater the heat transfer coefficient. The wall thickness of the copper tube cannot be less than 1.2mm due to strength and wear, and the wall thickness of the stainless steel tube can be as thin as about 0.5-0.8mm, so now people Most of them choose stainless steel tubes as heat exchange tubes.

2. The smoothness of the surface of the heat exchange tube will also affect the heat exchange effect. Common heat exchange tubes include smooth surface tubes and threaded tubes with threads. Compared with the heat transfer tube, when the threaded tube is used as the heat transfer tube, in the formal heat transfer process, the medium flowing inside the spiral tube will rotate along the spiral tube around its radius of curvature, which will cause the tube to be radial and circumferential. The heat transfer coefficient of the convection becomes larger, so the heat transfer effect of the spiral tube is better. Therefore, the heat exchange tubes in the industrial production that we see daily are mostly stainless steel threaded tubes. In addition, the surface structure of specially designed heat exchange tubes such as corrugated tubes will have a much better heat exchange effect than that of bare tubes, which can improve the overall heat exchange effect of the heat exchanger.

3. The thickness and shape of the inner wall of the heat exchange tube will also affect the heat exchange effect. Stainless steel corrugated tube is a commonly used heat exchange tube in heat exchange equipment. Its enhanced heat transfer is achieved through its unique ultra-thin-walled corrugated tube. The inner shape is like a candied haws-like thin-walled tube. The height difference between the wave crest and the trough makes The fluid is strongly disturbed, even if the fluid velocity is very low, it can be made into a turbulent state; at the same time, the thin tube wall has a small temperature gradient, which greatly reduces the thermal resistance of the tube wall and improves the heat transfer coefficient inside and outside the tube, thereby enabling the overall heat transfer The coefficient increases.