Among the shell-and-tube heat exchangers, the simplest is the single-tube heat exchanger. If the heat transfer surface needs to be increased, the method of increasing the number of tubes is generally used. After the number of tubes is increased, the tube bundle can be divided to prevent the increase of the number of tubes. Afterwards, the flow velocity in the tube and the heat transfer coefficient are reduced. From the perspective of manufacturing, installation and operation, an even number of tube passes is generally used and the number of passes should not be too many.
Radiant Tubes and Recuperators