U-tube heat exchanger bends the heat exchange tubes into a U shape, with both ends fixed on the same tube sheet. Since the shell and the heat exchange tubes are separate, the tube bundle can expand and contract freely without generating temperature difference stress due to the temperature difference of the medium. The U-tube heat exchanger has only one tube sheet, no floating head, and a relatively simple structure. The tube bundle can be freely pulled out and inserted for easy cleaning, offering the advantages of a floating head heat exchanger. However, because the heat exchange tubes are bent into U-shapes with different radii, only the outermost tube can be replaced if damaged; other damaged tubes must be plugged. Additionally, compared to the fixed tube sheet heat exchanger, due to the bending radius limitation, there is a gap in the center of the tube bundle, allowing fluid to easily short-circuit, affecting heat transfer efficiency.
Basic Introduction:
In a tubular heat exchanger, two fluids exchange heat: one flows inside the tubes, its path called the tube side; the other flows outside the tubes, its path called the shell side. The tube wall serves as the heat transfer surface. To enhance the heat transfer coefficient of the shell-side fluid, a certain number of transverse baffles are usually installed inside the shell. These baffles not only prevent fluid short-circuiting and increase fluid velocity but also force the fluid to cross the tube bundle multiple times along a specified path, significantly increasing turbulence. Common baffles include segmental and disc types, with the former being more widely used. Each time the fluid passes through the tube bundle inside the tubes is called one tube pass, and each time it passes through the shell is called one shell pass. To increase the fluid velocity inside the tubes, appropriate partitions can be set inside the end caps to evenly divide all tubes into several groups. Thus, the fluid can pass through only part of the tubes each time and travel back and forth through the tube bundle multiple times, known as multiple tube passes. Similarly, to increase the shell-side velocity, longitudinal baffles can be installed inside the shell to make the fluid pass through the shell space multiple times, called multiple shell passes. In a tubular heat exchanger, due to the temperature difference between the fluids inside and outside the tubes, the temperatures of the shell and tube bundle also differ.
Note: The above information and technical parameters are compiled and released by Yangzhou Dare Electric Co., Ltd.
