Shell and Tube Heat Exchanger
A heat exchanger is a piece of equipment that continually transfers heat from one medium to another in order to carry process energy.
The natural laws of physics always allow the driving energy in a system to flow until equilibrium is reached. As long as there is a temperature difference, heat leaves the hottest fluid and will be transferred to the colder fluid. A heat exchanger is a piece of machinery designed solely for the transfer of heat energy between two mediums, it is therefor necessary that it has large contact surface areas of material separating each medium.
The theory of heat transfer from one media to another, or from one fluid to another, is determined by several basic rules:
About Heat Exchangers
Heat exchangers are devices used to transfer heat from one fluid to another while preventing the two from mixing. Heat exchanger manufacturers can make three main types: shell and tube heat exchangers, air-cooled heat exchangers and plate heat exchangers. Generally, a metal wall partition, acting as a conductor, is between the two fluids. A hot solution flowing on one side of the barrier transfers its heat to a cooler solution flowing on the other side. Thermal energy only flows from the hotter to the cooler in an attempt to reach equilibrium. The surface area of a heat exchanger affects its speed and efficiency: the larger a heat exchanger’s surface area, the faster and more efficient the heat transfer.
About Shell and Tube Type Heat Exchangers
Shell and tube type heat exchanger consist of a bundle of parallel sanitary tubes with the ends expanded in tube sheets. The bundle is contained in a cylindrical shell. Connections are such that the tubes can contain either the product or the media, depending upon the application. The major limitation is that they cannot be used to regenerate, but they can transfer a large amount of heat due to the large surface area.
Heat exchanger manufacturers typically construct their products of steel, titanium, copper, bronze, stainless steel, aluminium or cast iron. One of the biggest problems with heat exchangers is corrosion, which is common due to the constant flowing of liquid. Unfortunately, this is very difficult to avoid. To help prevent this, heat exchanger manufacturers need tubing that is resistant to general corrosion, pitting, stress-corrosion cracking (SCC), selective leaching and oxygen cell attack. Some heat exchanger designs incorporate fins to provide greater thermal conductivity, which also helps.
Most plate type heat exchangers will have titanium plates, titanium is almost totally impervious to corrosion caused by seawater and guarantees a long life providing it is properly maintained.
Shell and tube heat exchangers are constructed from a mixture of copper, nickel, titanium, steel or aluminium depending on there applications. Each part may have different materials depending on what is flowing through it.
Different Applications of Heat Exchangers
Although they are not always known by the name “heat exchanger,” these devices are quite common and aren’t always industrial-types. For instance, a car’s radiator is a useful device for transferring heat from the engine to the air. Other examples of commercial uses for heat exchangers include spa and swimming pool heating, home radiators, hot water radiators, refrigerators and air conditioners. Whether in commercial or industrial use, heat exchangers are vital as energy and money saving devices since most mechanical, chemical and energy systems require heat transferral of some sort.
Custom heat exchangers perform a crucial role in the design, operation and maintenance of heating and air-conditioning systems, vehicle design, power plants, refrigeration, chemical and industrial engineering systems. They are also important in settings such as food processing, industrial engineer processes, pharmaceutical, pulp and paper and the steel industry. All power generation industries need them. Other industries that use heat exchangers include aerospace, chemical, marine, semiconductor, petrochemical, electronic, automotive, water treatment facilities and textiles.