Stainless steel boiler tubes in the tube (also known as shell-and-tube type) heat exchanger more use, the number of larger pipes! It has a long history of industrial application, and still occupies a dominant position in all heat exchangers. Tube heat exchanger is mainly composed of shell, tube bundle, tube sheet and head. The shell is mostly circular, with parallel tube bundles installed inside, and the two ends of the tube bundle are fixed on the tube sheet.
There are two kinds of fluids for heat transfer in tube heat exchanger, one is flowing in the tube, and the other is flowing outside the tube, the stroke is called shell. The wall of the tube bundle is the heat transfer surface. In order to increase the heat transfer coefficient outside the tube, a number of transverse baffles are usually installed in the shell. Baffles not only prevent short circuit and increase fluid velocity, but also force fluid to cross-flow through the tube bundle many times according to the prescribed path, thus greatly increasing turbulence. There are two kinds of commonly used baffles, circular and circular, and the former is widely used. Every time a fluid passes through a tube in a pipe, it is called a tube pass once. It is called a shell process once through the shell. In order to increase the velocity of the fluid in the pipe, appropriate separators can be set in the heads at both ends, and all the pipes can be divided into several groups evenly. In this way, the fluid can be run back and forth several times at a time through only part of the pipe. Similarly, in order to increase the velocity of flow outside the tube, longitudinal baffles can be installed in the shell to make the fluid pass through the shell space many times, which is called multi-shell pass. In tube heat exchangers, the temperature of shell and tube bundle is different due to the different temperature inside and outside the tube.
