"Heat Exchangers Explained"

Heat exchangers are basically used to transfer heat. Examples where these are used include air-conditioning, car radiators, and fridges. So, what types of heat exchangers are there?
Shell and Tube Heat Exchangers
As the name suggests, this kind is composed of two types of tube or tube bundles. The first set is filled with the liquid that needs to be either heated up or cooled down. The second set runs next to the first and either heats this set up or cools it down. The shell is the section that surrounds the tube bundles. In general, shell and tube heat exchangers are used in high-pressure and high-temperature operations. Applications include power plants and steam engine locomotives.
Brazed Heat Exchangers
These heat exchangers are a form of plate heat exchanger. They're composed of a number of plates placed parallel to each other with a slight space in between each. Holes in the plates allow fluid to flow between them, and so heat can be transferred. With the more recent introduction of brazing, achieved with a vacuum furnace, heat exchange has become more effective. Also, because this design is smaller than shell and tube exchangers, it can be more effective in certain applications.
Plate Fin Heat Exchangers
In this design, heat is moved between fluids through finned chambers and plates. It's composed of a number of corrugated sheets, each of which is separated by smooth, metal plates. This results in finned chambers. Both hot and cold fluids flow through different layers. The heat transfer occurs through the fins, which also strengthen the structure of these heat exchangers. The fins can come in a number of types: plain, perforated, serrated, and herringbone. Basically, heat moves via a fin to a plate through to the next fin and then onto the subsequent flowing fluid. A main drawback in this design is that it's hard to clean.
Pillow Plate Heat Exchangers
These exchangers are used for cooling purposes. One main example is for cooling milk in the diary industry. A pillow plate is made by spot welding together a thick sheet of metal with a thinner sheet. It gets its name from the bulging appearance it has, which allows the liquids to move. Its design is created due to the fact that the sheets are welded either in a dotted or serpentine pattern. Then, when this enclosed space is put under high pressure, the thinner metal bulges out.
Fluid Heat Exchangers
This involves a shower of liquid through which a gas is pumped. The fluid is then transferred to another area, where it's cooled. The main function of such an exchanger is to cool down gases, but simultaneously, it also removes any contaminants. One application is in espresso machines.
The main role of heat exchangers can be found in their name: They transfer heat. There are a number of types available, each of which has its own benefits and advantages within certain fields and applications.