The core working principle of a horizontal heat exchanger is to achieve heat exchange between the two media in the tube side and the shell side through heat conduction through the tube wall or shell wall. Cross-flow or baffled heat exchange forms are often used to enhance the heat transfer effect.

The specific working process is as follows: two media with different temperatures flow in the tube side (the internal channel of the heat exchange tubes) and the shell side (the channel between the heat exchange tubes and the shell). The tube side medium usually flows horizontally and in a straight line along the tube bundle, while the shell side medium undergoes multiple back-and-forth flows between the tube bundles due to the obstruction of the baffles inside the shell, significantly increasing the contact time and contact area between the two media. The higher-temperature medium transfers heat to the tube wall, and then the tube wall transfers heat to the lower-temperature medium on the other side, ultimately achieving the heat exchange purpose of cooling the high-temperature medium and heating the low-temperature medium.

The baffles in horizontal heat exchangers also serve to support the heat exchange tubes and prevent them from deforming, and are widely used in chemical, petroleum, refrigeration and other industries that require high-precision heat exchange.