Heat exchangers are key components of industrial process systems. Their function is to transfer heat between two different media without the media coming into contact with one another. Heat exchangers are used, amongst other things, in the energy sector, the food industry, the chemical industry, the pharmaceutical industry, and in district heating and cooling systems.
Due to the wide variety of applications, there are several types of heat exchanger type has been developed. When selecting the appropriate equipment, key factors to consider include the type and composition of the media, temperature, pressure, volumetric flow rate and mass flow rate, the required heat output, and maintainability is also an important consideration.
What types of heat exchangers are there?
There are several different designs used in the industry. The most important ones are:
- Gasketed plate heat exchangers (GPHE)
- brazed plate heat exchangers (BPHE)
- welded plate heat exchangers (WPHE)
- shell-and-tube heat exchangers, (tube-bundle heat exchangers, (STHE))
- double-pipe heat exchangers (DPHE)
- coil heat exchangers (SHE)
- finned-tube and air-cooled heat exchangers (FTHE)
- plate-and-fin heat exchangers (PFHE)
Each type has different properties, which is why they may be ideal for different technological tasks.
1. Gasketed plate heat exchanger
A gasketed plate heat exchanger one of the most commonly used types of industrial heat exchanger.
The unit consists of stacked, pressed heat-transfer plates. Separate flow channels are formed between the plates for the two media. Heat is transferred from one medium to the other through the plates.
One of the greatest advantages of a plate heat exchanger is its large heat transfer surface area and compact design.
Why is a gasketed plate heat exchanger advantageous?
- high heat transfer efficiency,
- compact design,
- a collapsible structure,
- the discs can be cleaned,
- the seals can be replaced,
- The heat transfer surface can be extended or modified as required.
In an industrial environment, a particularly important advantage is the maintainability. Once the heat exchanger has been dismantled, the plates can be inspected and cleaned individually.
Gasketed plate heat exchangers are used in a wide range of applications, such as industrial heating and cooling systems, district heating, the energy sector and food processing technologies.
2. Brazed plate heat exchanger
A brazed heat exchanger Its design is similar to that of a plate heat exchanger, although the plates are joined together by soldering.
As there is no need for conventional rubber seals or a frame, the equipment can be extremely compact.
Common areas of application:
- HVAC systems,
- cooling systems,
- domestic hot water systems,
- small-scale industrial technologies.
Its advantages are its compact size and good heat transfer. However, unlike a conventional gasketed plate heat exchanger, the unit cannot be easily dismantled, which makes certain maintenance and cleaning tasks more difficult to carry out.
3. Welded plate heat exchanger
A welded plate heat exchanger In this case, the plates are joined by welding. This also allows for use in applications where, due to the temperature, pressure or properties of the medium, a conventional gasketed design is less suitable.
Welded structures are particularly common in specialised industrial applications.
There are semi-welded heat exchangers as well, which combine the advantages of welded and gasketed technology.
4. Tube-and-shell or jacket-and-tube heat exchanger
A bundled, or in English shell-and-tube heat exchanger, one of the classic solutions for industrial heat transfer.
The unit comprises a bundle of tubes housed within a jacket of larger diameter. One fluid flows through the tubes, whilst the other flows on the outside of the jacket.
Due to their robust design, shell-and-tube heat exchangers can be used in a wide range of industrial applications.
Common areas:
- power stations,
- energy systems,
- chemical industry,
- oil and gas industry,
- food industry,
- various technological systems.
There are several possible designs, such as fixed tube-and-plate, pull-out tube-bundle or U-tube designs.
5. Double-tube heat exchanger
The double-tube heat exchanger has a simple design: a smaller tube is housed inside a larger tube.
One of the fluids flows through the inner tube, whilst the other flows through the annular space between the two tubes.
Due to its simple design, it is easy to manufacture and maintain. It is primarily a suitable solution for applications with low or medium heat loads.
However, in the case of higher heat output, the required heat transfer surface area may result in a significant space requirement.
6. Coil heat exchanger
The spiral heat exchanger consists of two spirally shaped flow channels. The two fluids flow through separate channels, and heat is transferred via the metal surface separating the channels.
The design may also be advantageous in the case of certain contaminated or viscous media.
Spiral heat exchangers are used, for example, in the chemical industry, the food industry and in various technological heat recovery systems.
7. Finned-tube and air-cooled heat exchangers
If one of the media involved in the heat exchange is air or another gas, the following is often used finned tube heat exchanger.
The ribs on the outer surface of the tubes increase the heat transfer surface area, thereby improving heat transfer between the air and the fluid flowing through the tube.
In industry, various air coolers, for example, operate on this principle, and fin-fan heat exchangers.
Typical applications may include:
- in power stations,
- in the oil and gas industry,
- in the case of compressors,
- in industrial cooling systems,
- in ventilation systems.
8. Plate-and-fin heat exchanger
In plate-and-fin heat exchangers, the combination of plates and fins ensures a large heat transfer surface area.
Due to their compact design, they can be advantageous in applications where space is limited, whilst high heat transfer capacity is required.
Such heat exchangers are also found, for example, in gas industry and cryogenic technologies.
How do we choose the right heat exchanger?
The appropriate industrial heat exchanger The selection is not based solely on thermal output. When designing and selecting the equipment, several technical factors must be taken into account.
Key considerations:
Properties of media
What type of liquid or gas flows through the heat exchanger? Does it contain solid particles, fibres or other contaminants?
- Temperature
What are the required inlet and outlet temperatures? - Press
What are the operating and maximum permissible pressures? - Volume flow / Mass flow
What is the volume of fluid that passes through the heat exchanger per unit of time? - Heat transfer surface
How large an area is required to achieve the desired heat output? - Material quality
Depending on the properties of the medium, it may be important, for example, to use stainless steel, titanium or other specialised materials. - Maintainability
It is also important not to overlook how the heat exchanger can be cleaned and repaired during subsequent operation, as most operational faults are caused by a lack of maintenance.
Maintaining a heat exchanger is just as important as choosing one
Even a properly selected heat exchanger can lose some of its efficiency if it is not properly maintained over a long period of time.
Over time, limescale, corrosion products, sludge or other contaminants may build up on heat transfer surfaces. This can reduce heat transfer, increase pressure loss and, in extreme cases, lead to operational failure or leaks.
A heat exchanger maintenance During this process, it may therefore be necessary to:
- for dismantling,
- for cleaning plates or pipes,
- to replace seals,
- for inspecting plates and components,
- for a pressure test,
- for assembly,
- and a documented handover.
From this point of view, gasketed plate heat exchangers are particularly easy to maintain, as the unit can be dismantled, the plates can be inspected and cleaned individually, and the gaskets can be replaced if necessary.
When should you seek professional help?
If a heat exchanger’s performance deteriorates, pressure loss increases, a leak occurs, or the unit needs cleaning, it is advisable to have the problem assessed by a specialist.
In many cases, regular maintenance can prevent more serious breakdowns and the resulting unplanned downtime.
Alfa Grade – maintenance and repair of industrial heat exchangers
From Alfa Grade It specialises in the maintenance, repair and refurbishment of industrial heat exchangers.
First and foremost Alfa Laval heat exchangers and spare parts We have experience in this field, and we also undertake the maintenance and repair of equipment from other manufacturers.
Our services include, amongst others:
- dismantling and cleaning of plate heat exchangers,
- seal replacement,
- inspection of heat exchanger plates,
- assembly of heat exchangers,
- pressure test and leak test,
- condition assessment of heat exchangers,
- as well as the procurement of spare parts and heat exchangers where necessary.
Regular maintenance can not only extend the service life of the heat exchanger, but can also contribute to the more reliable and efficient operation of the process system.
Do you need your heat exchanger serviced or repaired? Please get in touch with us so that we can discuss the technical options for your specific unit.
