A heat exchanger is a piece of equipment that continuously transfers heat from one medium to another. There are two main types of heat exchangers: direct and indirect.
- Direct heat exchanger, where both media are in direct contact with each other. It is assumed that the fluids do not mix with each other. An example of this type of heat exchanger is a cooling tower, where water is cooled by direct contact with air.
- Indirect heat exchanger, in which two fluids are separated by a wall through which heat is transferred.
Indirect heat exchangers are available in several main types (plate, shell, tube, corrugated tube, spiral, etc.). In general, the corrugated steel tube offers the best solution to thermal problems, providing the widest pressure and temperature limits.
Operating principles
In an indirect heat exchanger, heat is transferred mainly through conduction and convection:
- Conduction: Heat is transferred through the walls of the heat exchanger.
- Convection: Heat is transferred between the exchanger walls and the moving fluids.
Everything is based on the theory of heat transfer.
The natural laws of physics always allow conduction energy in a system to flow until equilibrium is reached. Heat leaves the hotter body or the hotter fluid, as long as there is a temperature difference and is transferred to the cold medium.
A heat exchanger follows this principle in its effort to achieve equalization. With a heat exchanger, heat penetrates the surface, which separates the hot medium from the cold medium very easily.
Therefore, it is possible to heat or cool fluids or gases having minimum energy levels. The theory of heat transferfrom one medium to another, or from one fluid to another, is determined by several basic rules:
- Heat will always transfer from a hot medium to a cold medium.
- There must always be a temperature difference between the media.
- The heat lost by the hot medium is equal to the amount of heat gained by the cold medium, except for losses to the surroundings.
Common types of indirect heat exchangers
Concentric tube heat exchanger (Double Tube):
- It consists of a tube inside a larger tube.
- One of the fluids flows through the inner tube and the other flows through the annular space between the two tubes.
- They can be configured in parallel flow or counterflow.
Shell and tube heat exchanger:
- Composed of a bundle of tubes contained in a casing.
- One fluid flows through the tubes and the other fluid flows through the casing around the tubes.
- The configuration can be parallel flow, counterflow or crossflow.
AZ INTEC Heat Exchangers
In this context, AZ INTEC’s heat exchangers from AZ INTEC heat exchangers that we develop and produce at our production sites in Germany and the Czech Republic are used in industrial applications and in building services management (HVACR).
For example: storage tanks, cooling systems or DHW boilers. We carry out complex studies and assemblies for our customers thanks to our experienced knowledge in this field.
All our heat exchangers meet the requirements for applications in domestic water cycles.
Interested? Contact us for more information.