The tubular heat exchanger, also known as a shell-and-tube heat exchanger or tube-bundle heat exchanger, is a type of interwall heat exchanger that uses the wall surface of a tube bundle enclosed within a shell as the heat transfer surface. It is the most typical interwall heat exchanger. Below is a detailed introduction to its features:
Structural Composition: It mainly consists of a shell, tube bundle, tube sheets, and headers. The shell is typically cylindrical and contains a parallel tube bundle, with both ends of the tube bundle fixed to the tube sheets. To enhance the heat transfer coefficient of the fluid outside the tubes, a certain number of transverse baffles are usually installed inside the shell. Common types of baffles include segmental and disc-shaped designs.
Working Principle: Two fluids flow inside and outside the tubes, respectively. The flow path inside the tubes is called the tube side, while the flow path outside the tubes is called the shell side. The wall surface of the tube bundle serves as the heat transfer surface. The hot fluid transfers heat to the tube wall via convection, and the heat is then conducted through the tube wall to the cold fluid on the other side, completing the heat exchange process.
Common Classifications
Fixed Tube Sheet Heat Exchanger: The tube sheets at both ends are directly welded to the shell. It features a simple structure, low cost, ease of manufacturing, and convenient cleaning and maintenance of the tube side. However, cleaning the shell side is difficult, and thermal stress exists in the tube bundle after manufacturing. When there is a significant temperature difference between the tubes and the shell, an expansion joint must be installed on the shell.
Floating Head Heat Exchanger: One tube sheet is fixed between the shell and the tube box, while the other tube sheet can move freely within the shell. This design allows free thermal expansion of the tube bundle and shell, eliminating thermal stress. The tube bundle can be easily removed and reinstalled, facilitating cleaning and maintenance. However, the structure is relatively complex, and the sealing requirements are higher.
U-Tube Heat Exchanger: The heat exchange tubes are bent into a U-shape and fixed to the same tube sheet at both ends. Since the shell and tubes are separate, the tube bundle can expand and contract freely without generating thermal stress. The structure is relatively simple, and the tube bundle can be easily removed and reinstalled for cleaning. However, replacing damaged tubes is difficult, and gaps in the center of the tube bundle may affect heat transfer efficiency.
Performance Characteristics: Compared to modern heat exchangers, tubular heat exchangers are less efficient in terms of heat transfer efficiency, structural compactness, and metal material consumption. However, their simple structure, low cost, ability to withstand high temperatures and pressures, mature manufacturing processes, strong adaptability, and wide range of material options make them dominant in engineering applications.