Shell and tube heat exchanger
The shell and tube heat exchanger (RWÜ) (engl .: shell and tube heat exchanger ) is a thermal apparatus for transferring heat energy from one body to a second. Sometimes a tube bundle heat exchanger is also called a "recuperator" because, in contrast to regenerators, it transfers the heat without intermediate storage. The term tube bundle heat exchanger is still widely used . This term, like the DIN designation tube bundle heat exchanger, is misleading, since heat is only transferred from the hot medium to the cold one and is not exchanged.
Shell and tube heat exchangers are indirect heat exchangers because the heat is transferred through walls and the two media are separated. An exchange of substances is therefore not possible.
Technically, the tube bundle heat exchanger is realized by a hollow cylinder made of sheet steel , inside of which there are hundreds to thousands of tubes with a small nominal diameter . The first medium flows through the sheet metal cylinder, the second through the pipes. During this process, the hotter medium cools down while the colder medium is heated up.
Depending on the mode of operation and the direction of flow of the media, a distinction is made:
- Countercurrent recuperators
- Cross-flow recuperators
- DC recuperators
The transfer of heat is best guaranteed with a countercurrent recuperator, whereas with a directcurrent recuperator the heat is not transferred as well, but the directcurrent recuperator is better suited for rapid cooling / heating. The performance of the cross-flow recuperator lies between the two other types.
Examples of tube bundle heat exchangers:
- Capacitor as a cross-flow recuperator
- Oil cooler on large machines, mostly operated as a counterflow recuperator, also as a safety cooler
- Exhaust gas heat exchangers in industrial processes
Recuperators are used to recover waste heat from ovens. The hot exhaust gases are passed through ducts or pipes, on whose heated walls the gases drawn into the furnace are heated. The wall that conveys the heat can be made of heat-resistant steel, cast iron or ceramic. Recuperators are connected downstream of the heating and annealing furnaces, they improve their efficiency and increase the furnace temperature.
Tube bundle heat exchangers are widely used in the chemical industry and in the food industry. They are used there in a variety of ways for heating, evaporating , cooling and condensing media.
Web links
- Tubular Heat Exchanger Manufacturing Association (English)
- Engineeringpage / Heat Exchangers - English-language page on heat transfer with material values, calculator, etc. Ä.
Selected standards
- DIN 28008 tolerances and limit dimensions for tube bundle heat exchangers
- DIN 28183 shell and tube heat exchangers - designations
- DIN 28185 internals for tube bundle heat exchangers
- DIN 28190 tube bundle heat exchanger with welded floating head - exemplary embodiments for tube arrangement and floating head