| Customization: | Available |
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| Certification: | ISO 9001 |
| Application: | Heater, Cooler, Vaporizer, Condenser |
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The shell-and-tube heat exchanger, also known as a tubular or columnar heat exchanger, is the most typical type of partitioned heat exchanger. It has a long history of industrial use and still holds a dominant position among all heat exchangers. This type of heat exchanger primarily consists of a shell, tube bundles, tube sheets, and end caps, with the shell usually being cylindrical and containing parallel tube bundles fixed at both ends to the tube sheets. In shell-and-tube heat exchangers, two fluids facilitate heat exchange-one flowing inside the tubes, known as the tube-side, and the other outside the tubes, known as the shell-side. The walls of the tube bundles serve as the heat transfer surfaces. To enhance the heat transfer coefficient of the fluid outside the tubes, a number of transverse baffles are typically installed within the shell. These baffles not only prevent fluid short-circuiting and increase fluid velocity but also force the fluid to flow through the tube bundle multiple times in a cross-current manner, significantly increasing turbulence. The most commonly used baffles are segmental and disc-type, with the former being more widely utilized. Each pass of the fluid through the tubes is called a tube pass, and each pass through the shell is called a shell pass. To increase the velocity of the fluid inside the tubes, appropriate baffles can be placed in the end caps, dividing the tubes into several groups. This allows the fluid to pass through only a portion of the tubes and reciprocate multiple times, known as multiple tube passes. Similarly, to increase the velocity outside the tubes, longitudinal baffles can be installed inside the shell, allowing multiple shell passes. Fixed tube sheet heat exchangers weld the tube sheets directly to the shell at both ends. Composed mainly of the outer shell, tube sheets, tube bundle, and end caps, the tubes are affixed to the tube sheets using welding, expansion, or rolled joints, and the periphery of the tube sheet and the end cap flange are bolted together. While this type of heat exchanger has a simple structure, is inexpensive to manufacture, and facilitates easy cleaning and maintenance of the tube side, cleaning the shell side is challenging, and temperature-induced stresses can exist post-manufacture. When there is a significant temperature differential between the heat exchange tubes and the shell, an expansion joint may also be necessary on the shell. Floating head heat exchangers feature one end of the tube plate fixed between the shell and the tube box, with the other end able to move freely within the shell, thus allowing free thermal expansion between the shell and tube bundle and eliminating thermal stress. Typically, the floating head is removable, and the tube bundle can be easily extracted and reinserted. This structure is suitable for conditions where there is a significant temperature difference between the tube bundle and the shell. It provides convenient cleaning and maintenance for both the tube bundle and shell, but the structure is relatively complex and requires high sealing performance. U-tube heat exchangers bend the heat exchange tubes into a U-shape, with both ends fixed to the same tube sheet. Since the shell and the heat exchange tubes are separate, the tube bundle can expand freely without stress from temperature differences in the medium. U-tube heat exchangers have a single tube sheet and no floating head, making their structure simpler. The tube bundle can be freely extracted and inserted for easy cleaning, combining the advantages of floating head heat exchangers. However, because the heat exchange tubes are bent into varying radii, only the outermost damaged tubes can be replaced; others must be plugged if damaged. Additionally, compared to fixed tube sheet heat exchangers, the central part of the tube bundle has gaps due to the bending radius, which can lead to fluid short-circuiting and impact heat transfer effectiveness. |
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