The sleeve type heat exchanger is a concentric sleeve made of straight tubes of different diameters and connected by a U-shaped elbow. Because the fluid flow rate outside the tube is large. The cold and hot fluids can be used as pure countercurrent, so the heat transfer coefficient is large and the heat transfer effect is good. The commonly used water heating is a simple casing heat exchanger.
Shell-and-tube (also known as tube-and-tube) heat exchangers are the most typical type of wall-mounted heat exchangers. They have a long history in industrial applications and still dominate the heat exchangers.
In order to increase the heat transfer coefficient of the fluid outside the pipe, a certain number of transverse baffles are usually installed in the casing.
The baffle not only prevents fluid short circuit, increases fluid velocity, but also forces the fluid to flow through the tube bundle multiple times in a prescribed path, so that the degree of turbulence is greatly increased. Commonly used baffles are rounded and disc-shaped, the former is more widely used.